Hundreds of protesters gathered in Sydney’s Hyde Park on Friday to protest against Cambodian strongman Hun Sen, who claimed to have been gifted millions of dollars by the Australian government ahead of a special Asean summit this weekend.

An estimated 300 protesters, the majority of them from the Cambodian-Australian community, carried signs calling for the release of jailed opposition leader Kem Sokha.

Sokha was arrested in September and charged with “treason”, an allegation widely believed to be politically motivated. Two months later, his party – the only real challenger to the ruling Cambodian People’s Party at the July 2018 election – was forcibly dissolved.

There was a strong police presence at the event, after Hun Sen previously made threats to follow would-be protesters home and beat them if they burned his photo. While no effigy of the premier was set alight at the event in Hyde Park, effigies have been burned at a previous protest.

Several monks draped in orange chanted a prayer in Pali before a minute of silence was held to remember figures widely believed to be victims of political assassinations in Cambodia, including beloved political analyst Kem Ley.

Ley’s widow Bou Rachana, who has relocated with her family to Melbourne, thanked the crowd for their support. One monk, Venerable Nou Sorng, pleaded with the Australian government to urge Hun Sen to respect human rights.

"Hun Sen always take his own people as hostage…using violence, intimidating them,” he said. “He even threatens his people if they don’t vote for the [Cambodian People’s Party]. They will not develop anything in Cambodia.”

“We can’t describe all Hun Sen’s bad activities,” he said. “He must release Kem Sokha and reinstate the CNRP back to politics.”

Earlier on Friday, Hun Sen met with scores of Cambodian-Australian supporters on the streets of Sydney, shaking hands and posing for selfies.

“I just met with the Prime Minister of Australia,” he said. “They will provide us financial assistance of $78 million.”

An Australian Department of Foreign Affairs and Trade spokesman said that the "amount of Australia's development assistance to Cambodia has not changed". "It remains at AU$87.4 million for the financial year 2017-18," they wrote in a statement on Saturday.

Hun Sen said the funds would be “cash assistance” and that other offers of assistance were made as well. Government mouthpiece Fresh News reported Kao Kim Hourn, minister delegate to Prime Minister Hun Sen, as saying the money would be aid for “development in Cambodia”.

Any such aid would be at odds with other international moves of late. The US severed aid to the Kingdom following a Cambodian People’s Party sweep of seats at the Senate elections last month.

It is also at odds with demands from opposition politicians and rights groups, both from Australia and Cambodia, which have repeatedly urged Prime Minister Turnbull to take Cambodia to task for its widespread crackdown on political opposition, independent journalism and civil society.

Human Rights Watch Australia Director Elaine Pearson, who spoke at the protest on Friday, said Hun Sen had, for three decades, “repeatedly used political violence, intimidation and corruption to stay in power”.

“This latest cycle of violence and repression is especially fierce,” she said. “Do not embolden Hun Sen to crack down harder on his people because he sees there is no cost to these actions.”

“This protest is important. While the Australian government may try and airbrush human rights issues out of the summit, Australians stand in solidarity with the people of Cambodia and we will speak out against Hun Sen’s ongoing crushing of dissent.”

Australian-Cambodians are planning to take part in another protest on Saturday, in conjunction with members of the Filipino, Roghingya and Vietnamese communities to demonstrate against a raft of human rights abuses in Southeast Asia.

Also on Friday, former CNRP president Sam Rainsy appealed for the release of Australian filmmaker James Ricketson, who was charged with espionage after flying a drone over an opposition rally. On Facebook, Rainsy urged Hun Sen to free Ricketson, who has been in jail since June. “Ricketson has been held hostage by Hun Sen in order to deter other foreign journalists from writing the truth about his authoritarian and corrupt regime,” Rainsy wrote.