Tens of thousands of protesters, undeterred by the arrests of opposition leaders, marched in Malaysia’s capital on Saturday demanding that Prime Minister Najib Razak step down, Reuters reported.

Protesters clad in yellow shirts marched through the heart of Kuala Lumpur bringing traffic to a standstill in several tourist spots, wrapping up peacefully in front of the iconic Petronas Twin Towers after an initial plan to assemble at Independence Square was thwarted by police.

Najib has faced criticism since the Wall Street Journal reported last year that around $700 million from state fund 1Malaysia Development Berhad (1MDB) was diverted into the personal bank account of the prime minister.

Najib ran into further trouble when lawsuits filed by the U.S. Justice Department in July said over $3.5 billion was stolen from 1MDB, which was founded by Najib, and that some of those funds flowed into the accounts of “Malaysian Official 1”, whom U.S. and Malaysian officials have identified as Najib.

The demonstration is unlikely to shake the prime minister, who has denied wrongdoing and weathered the crisis, consolidating power by cracking down on dissenters.

Eleven activists and opposition leaders were arrested on Friday and at least two more were detained at the rally. The deputy Prime Minister Ahmad Zahid Hamidi said there could be more arrests in the coming days.

Maria Chin Abdullah, the chair of pro-democracy group Bersih that organized the rally, was detained under Malaysia’s Security Offences (Special Measures) Act, or Sosma, her lawyers said. The law was introduced in 2012 to protect the country from security and extremist threats.

Laurent Meillan, acting regional representative of the United Nations Human Rights Office in South-East Asia, said the use of Sosma was very concerning.

“Security legislation should not be used against peaceful demonstrators. We call for the immediate and unconditional release of Maria Chin Abdullah and other activists,” Meillan said.

Another Bersih leader, Hishamuddin Rais, and artist Fahmi Reza were also arrested.

“We are not here to bring down the country. We love this country! We are not here to tear down the government, we’re here to strengthen it,” Bersih deputy chair Shahrul Aman Shaari told the crowds gathered at the National Mosque.

Najib has taken steps which critics say aim to limit discussion of the scandal, such as sacking a deputy prime minister, replacing the attorney-general, suspending newspapers and blocking websites.

Najib retains significant support within UMNO and from the long-ruling Barisan Nasional coalition.