HONG KONG-- Tens of thousands joined a rally in Hong Kong on Sunday to demand justice for victims of the Manila hostage bloodbath, as the city's Filipino community staged its own memorials for the dead.

Demonstrators voiced their anger over the Philippine government's handling of the siege in the heart of Manila on Monday, which left eight Hong Kong tourists dead amid widespread complaints of police bungling.

"It's too late for the governments to do anything, but Hong Kong people hope that, at the very least, the Philippine authorities could tell us the truth," Daisy Kwong, a telecoms firm project manager, told AFP.

"I cried for hours after watching the tragedy played out live on TV," she said.

The sea of demonstrators observed three minutes of silence as they gathered in a Hong Kong park Sunday afternoon, many wearing yellow ribbons and carrying white flowers, the traditional Chinese colour of mourning.

The Hong Kong political parties organising the rally have said it could draw as many as 50,000 people. No official figures have been released.

"I am furious," 56-year-old Law Wai-hing said. "I don't think we will ever be told the truth when the (Philippine) president (Benigno Aquino) is as appalling as he is.

"I hope the Chinese government and the United Nations can exert pressure on the Philippine government."

Members of the city's 200,000-strong Filipino community, the vast majority working as low-paid domestic helpers, have voiced fears of retribution.

Rally organizers asked demonstrators not to carry racially charged placards or chant discriminatory slogans, while several hundred Filipinos turned out to a candlelight vigil, one of several memorial services held Sunday.

"Please don't be upset. Don't be scared. It's not your fault. We share our anger towards the Philippine government, not towards you, not towards the entire nation," Fermi Wong, founder of Unison Hong Kong, a social group helping ethnic minorities, told the crowd of mainly domestic helpers.

Philippine vice consul Val Roque said that a text message was sent to members of the community asking them to "set aside what they are doing" and attend memorial masses on Sunday.

"Being mostly Catholic, it was the best way for us to express our solidarity with the people of Hong Kong," Roque told AFP.

He downplayed fears about possible reprisals on Filipinos, saying there had been no confirmed reports of harassment or physical abuse.

"We trust our friends in Hong Kong would not do anything untoward against Filipinos here... But we understand the anger must be released. We hope as the days go by that anger will dissipate."

A Facebook site to remember the victims has attracted thousands of signatures and a flood of criticism directed at the Philippine government.

Disgraced ex-policeman Rolando Mendoza, armed with an assault rifle, hijacked a busload of Hong Kong tourists on Monday in an apparent bid to win his old job back and be cleared of extortion charges.

Eight tourists and the gunman were killed in the final stages of the 12-hour ordeal, when ill-equipped police launched an assault on the bus in a drama that unfolded live on television screens around the world.

Philippine police said Sunday they were certain that the Hong Kong tourists were killed by Mendoza, rather than by police bullets during the ill-fated rescue operation.

Hong Kong undersecretary for security Lai Tung-kwok said on Saturday autopsies had been carried out on all eight victims, which may lead to an official inquiry.

Five senior Manila policemen who took part in the assault have been suspended and their commanding officer has also taken leave.

Hong Kong's Sunday Morning Post newspaper reported that a letter containing an offer by the Philippine police to suspend Mendoza's dismissal and try to end the hostage crisis had arrived at the scene too late.

But this claim was dismissed by country's national police spokesman.