Tens of thousands of Malaysians have streamed into central Kuala Lumpur to call for the prime minister’s resignation over corruption allegations and demand broader reforms.
They have ignored warnings by police who have declared the rally illegal.
The capital’s historic heart was jammed by huge crowds, most of them in the banned yellow T-shirts of Malaysia’s reform movement, amid a carnival atmosphere of political speeches, musical performances, deafening vuvuzelas and selfie-taking.
But they were prohibited from entering Independence Square for a planned overnight occupation of the area, with access blocked by security barriers manned by a large police presence.
Members of Prime Minister Najib Razak’s cabinet have admitted he received nearly $US700 million ($A977 million) in mysterious deposits into his personal bank accounts starting in 2013.
The revelation, brought to light by the Wall Street Journal last month, has angered many Malaysians, including members of Najib’s ruling party, already fed up with recurring government graft scandals.
Previous rallies organised by the civil-society movement Bersih have ended in clashes with police, most recently in 2012.
Bersih was first formed to press for reform of an electoral system it says is biased, propping up the ruling Barisan Nasional (National Front) coalition despite its flagging voter support.
Malaysian media outlets estimated the crowds at up to 80,000.
There were no incidents reported as of early Saturday afternoon and rally-goers were so far respecting the security cordon around the square.
Najib called the rally disrespectful towards Monday’s National Day.
Local media reported seeing trucks with water cannon being deployed earlier in the day. Police seen by AFP were not in riot gear.
Smaller gatherings also were reported in the cities of Kuching and Kota Kinabalu on Borneo island.
Rally organisers and opposition leaders said they intended to stay on the capital’s streets overnight.
Najib recently sacked officials or absorbed into his cabinet parliamentarians who were probing the matter, leaving the status of investigations unclear.
The premier had already been under pressure over months of allegations that huge sums had disappeared from deals involving heavily-indebted state investment company 1Malaysia Development Berhad (1MDB), which Najib launched in 2009.
Recent reports also have detailed alleged multi-million dollar overseas investments by Najib family members.
Najib and 1MDB vehemently deny wrongdoing.