Former Malaysia Prime Minister Mahathir Mohamad has called on protesters on the streets of Kuala Lumpur to "remove" the country's Prime Minister Najib Razak.
"To remove him, the people must show people's power," he said as he joined the protests for a second day running, undeterred by a heavy police presence.
Protesters are angered by a $700m (£455m) payment made to Mr Najib's bank account from unnamed foreign donors.
The prime minister denies any wrongdoing.
'No more rule of law'
Mr Mahathir said it was untenable for the current prime minister to continue in his position.
"There's no more rule of law. The only way for the people to get back to the old system is for them to remove this prime minister," he said. "We must remove this prime minister."
Mr Mahathir led Malaysia from 1981-2003. A former ally of the prime minister, he has since become a fierce critic of Mr Najib.
Police estimated 25,000 people participated in Saturday's demonstration, while Bersih - the pro-democracy group behind the rally - said 200,000 took part at the peak.
"Those who wear this yellow attire... want to discredit our good name, scribble black coal on Malaysia's face to the outside world,'' national news agency Bernama quoted Mr Najib as saying.
The main accusation against the prime minister is that he took $700m from the indebted 1MDB state investment fund, which he established in 2009 to try to turn Kuala Lumpur into a financial hub.
Cabinet ministers have said the money transfers were "political donations" from unidentified Middle Eastern sources, and that there was nothing improper. No further details have been given.
What is 1MDB?
• The 1Malaysia Development Berhad (1MDB) state investment fund was established under Prime Minister Najib Razak in 2009 to transform Malaysia into a high-income economy.
• Critics say the fund overpaid for many of its investments and spent millions on fees to investment bank Goldman Sachs
• It began attracting attention at the end of 2014 when it started missing payments to creditors. It later emerged that the fund was mired in $11bn (£7bn) of debt.
• Mr Najib has been accused of taking $700m from the fund - a charge which he has denied.
• Malaysia anti-corruption commission said it had verified that the money was a donation from unnamed foreign donors.
Read more: 1MDB, the case that's riveting Malaysia