The police are taking no chances and have set up roadblocks and sent out patrols specifically to clamp down on the gathering at the National Palace organised by the Pakatan Rakyat-led government to submit a memorandum to the ruler Sultan Mizan Zainal Abidin.
11.30am: PSM president Dr Nasir Hashim and his secretary-general and Kajang municipal councillor S Arutchelvan (right) are spotted by a team of police officers at KL Sentral near Brickfields.
They and one other activist are ordered to stay put until further instructions are received by police superiors.
When met at the spot where they were told to remain, Nasir tells Malaysiakini: "Saya tak pasti (ditahan). Polis halang saya (bergerak) sebab pakai baju merah," (I'm not sure if I'm under arrest. The police are holding me because I'm wearing red), says the Kota Damansara state assemblyperson.
12.05pm: Nasir confirms that he, Arutchelvan and one other activist have been arrested and brought to the Petaling Jaya district police station.
No reasons were given for the arrest, says Nasir.
"They say it was for illegal assembly. But we were only three in the group."
Elsewhere in Kuala Lumpur and Shah Alam, Selangor, roadblocks have been set up to stop people from attending the protest and submission of the memorandum.
Organisers of the rally have said they will march from Masjid Negara to the palace of the sultan.
According to a tweet by former PKR supreme council member, Badrul Hisham Shaharin, several 'marshalls' have also been arrested. He urges other participants in the rally to remain calm, and proceed to the Masjid Negara.
According to a tweet from DAP's Kampung Tunku state assemblyperson Lau Weng San, a TV Selangor cameraman, has also been arrested.
Others at Masjid Negara are Selangor exco Ronnie Liu (left), PAS' Kuala Selangor MP Dzulkifli Ahmad, Badrul Hisham, and PKR's Batu MP Tian Chua.
The roads leading to Masjid Negara have been closed.
At Stadium Merdeka, meanwhile, about 300 members of the anti-Selangor government group Gaps have gathered and are set to hold a press conference to voice their stand on the matter.
At Merdeka Stadium, meanwhile, there are around 300 people gathered at Stadium Merdeka, chanting 'Hidup Melayu!', 'Daulat Tuanku!', and '1Malaysia!'
Some, however, are at Masjid Negara, where the pro-Selangor government supporters are also gathering.
Gaps chief Hamidzun Khairuddin who is leading the anti-Selangor government group, denies that the participants of the demonstration are from Umno Youth or Wanita.
"They are all people from Selangor who care about the state," he tells a short press conference.
The former Selangor PKR youth chief also denies that Gaps are mobilising dancers from the government's Tarian 1Malaysia dance troupe under the Tourism Ministry at Dataran Merdeka earlier today to participate in the demostration.
They came by their own initiative, says Hamidzun.
When asked earlier, one of the female participants from the 1Malaysia dance at Dataran Merdeka just now, denies she is from Umno.
"We are from Selangor," she tells Malaysiakini.
One of the male participants also denies they are from Umno.
However, there is a sticker on a motorbike belonging to a Gaps supporter with an Umno logo, and the words 'Berbudi, Membalas budi, Mengenang Budi, Sukarelawan Kota Anggerik'.
Among the banners with them are those read: 'Khalid Ibrahim is a weak (Selangor) MB'; 'Crony of sand mining scandal steal people's money'; and 'Cruel MB robbing the land of Yayasan Bakti Keluarga'.
12.48pm: Eight delegates led by Gaps chief Hamidzun successfully submits the group's memorandum to the National Palace.
"We submitted the memorandum after negotiating with the police," he tells Malaysiakini when contacted.
The memorandum was received by one of the security officers of the palace.
The memorandum asks the King to intervene over the alleged irregularities that have occurred in the Selangor government.
The memorandum also points out 30 alleged irregularities, including claims that the govenment cheated the Selangor Sultan and that the people have failed to gain RM 150 million from sand revenue per year as promised by the Selangor MBl.
It states further that Selangor government has failed to manage the MB's office properly, a result of which somebody was able to hide camera in Khalid's office for some time without being detected.
12.57pm: In Masjid Negara (left), the crowd is shouting "Tolak Syabas, tolak BN! Hancur Syabas, hancur BN!"
1pm: The Gaps crowd at Stadium Merdeka disperses.
1.05pm: PKR deputy-president Azmin Ali, Selangor exco Dr Xavier Jeyakumar and Klang MP Charles Santiago are also seen at Masjid Negara.
1.43pm: By this time, about 7,000 people have gathered at Masjid Negara.
Speaking to the crowd, MB Khalid says 250,000 people have signed the state government's petition supporting its moves to regain control of water in the state.
Syabas increased the tariff by 37 percent last year, he adds.
The federal government should respect the spirit of federation and not side with the private sector and allow them to reap in higher profits at the expense of the people, says Khalid.
"The people of Kuala Lumpur, Putrajaya and Selangor will suffer!
"The state government will ensure the rights of the people will be preserved." The crowd shouts "Hidup Rakyat!"
2.15pm: Water cannons are let loose on the crowd marching from Masjid Negara to the Istana Negara near the KTM office.
About 2,000 people are caught at the roundabout nearby the masjid.
2.22pm: MB Khalid hands over memorandum with 250,000 signatures to Istana Negara officers. According to Selangor exco Teresa Kok, the police stop the delegation from taking pictures of the occasion.
2.24pm: A second group of about 2,500 that broke off from the first are heading towards Kampung Attap. Police are preparing to deal with this group.
2.40pm: The crowd at Kg Attap are retreating back towards the Masjid Negara and heading down Jalan Kinabalu. The police warn the crowd to disperse or face tough action.
2.46pm: Scores of FRU personnel are standing by near the National Palace to face the protestors.
3.13pm: Scores of people near the masjid are being dispersed by force. Klang MP Santiago in a tweet says he was "caught, kicked around, then let go."
3.15pm: Selangor exco Yaacob Sapari tells reporters the organisers are prepared to tell the crowd to disperse if the police release all those arrested so far.
The police are currently discussing with Kuala Selangor MP Dzulkefly Ahmad on how to get the crowd to peacefully disperse. Dzulkefly tells reporters the police will release 10 people.
The crowd is slowly dispersing, but some refuse to leave without their colleagues.
3.48pm: Dzulkefly asks the police for a fresh guarantee before the crowd disperses. Deputy KL police chief Amar Singh (left) says, “I promise no one else will be arrested as long as everyone disperses voluntarily and peacefully.”
The crowd agrees. A few individuals within the crowd are calling for the immediate release of those arrested. Dzulkefly and Shah Alam MP Khalid Samad (above, white skull cap) manages to convince the crowd.
“Those arrested, don't worry - we will work on it,” says Khalid.
According to Ampang MP Zuraida Kamaruddin, 47 people have been arrested from Masjid Negara so far, of which 5 are students.
Updated at 5.39pm
This is apart from Nasir, Arutchelvan and another activist from PSM who were arrested earlier this morning. The three were released around 1pm this afternoon.
According to Subang MP and lawyer R Sivarasa, however, a total of 52 have been arrested.
4.30pm: Most participants have dispersed, though some are still loitering at Masjid Negara. KL police chief Zulkefli Abdullah tells a press conference that a total of 48 people were arrested.
More updates from Malaysiakini later and I will update here.
Watch the video recording from Channel NewsAsia AT THIS LINK.
Anonymous From Bayu:
Clearly, the police are protecting the cronies instead of rakyat. Crime rates are no concern of the men in blue. Got manpower and time to clampdown on peaceful dissent. Allah selamatkan Malaysia.