CISARUA, Indonesia (Reuters) - Mystery deepened on Thursday over the events leading up to the deaths of 350 asylum seekers on board a fishing boat that sank off Indonesia last week as some survivors said uniformed men pointed guns at people who wanted to get off.

The police chief denied reports that a dozen police had protected the people smugglers, who organised the treacherous journey for the migrants from Indonesia to Australia.

Two survivors from last Friday's tragedy told Reuters they saw no police before the overcrowded boat left Sumatra island.

But two others said a number of armed men in uniforms would not let those who wanted to get off the leaky vessel do so before it sailed from Sumatra island. One said he believed the men were immigration officials.

The events highlight an increasing refugee problem for Jakarta and Canberra as more and more boats are setting out with their human cargo of Middle Eastern and Afghani asylum seekers bound for Australia, a country unwilling to take in boat people.

"I saw four of them, they were pointing their guns at us. I think they were immigration people," Jalal Mohsin, a 34-year-old Iraqi told Reuters in the town of Cisarua, south of Jakarta where the survivors are staying.

"I wanted to get off but they wouldn't let me," he said, adding he was confident the men were not police.

Ali Hameed Ahmad, 28, who said he was a Kurdish refugee, said he saw 30 armed men in uniform.

"Two (refugees) were beaten by the men in uniform. We were not allowed to get off," he said.

The Immigration Department could not be reached for comment.

DARK REMINDER

Only 44 refugees survived the sinking, one of Indonesia's worst maritime disasters and a dark reminder of the plight of thousands of refugees who use Indonesia as a springboard to try to reach Australia each year.

The boat was already leaking when it left Sumatra for Australia's remote Christmas Island, a popular landing target for asylum seekers. It sank off the coast of Indonesia's Java island.

"There was nothing like that," police chief General Bimantoro told reporters when asked about a report in Australia's Sydney Morning Herald which quoted survivors as saying police pointed their guns at asylum seekers who wanted to get off.

Survivor Ali Jawad, an Iraqi, told Reuters from his hospital bed that no police or other officials were present when the boat left Sumatra.

"There were no photographers, no police, just us," Jawad said in broken English.

The U.N. refugee agency and the International Organisation for Migration (IOM) earlier cautioned that the accusations had not been proven and they had come from traumatised people.

In the Herald report, survivor Kareem Jabar said an Egyptian smuggler smashed one migrant over the head with the butt of a gun when he wanted to take his family off the boat.

"When most of us saw the boat was too dangerous we wanted to get off and get our money back," the 25-year-old Iraqi was quoted as saying.

Referring to the same Egyptian smuggler, Kurdish survivor Ahmad told Reuters: "If I see him again, I will kill him."

Australia said it has informed Jakarta about an Eqyptian people smuggler operating out of Jakarta it says was responsible for the boat in question. Officials in Jakarta have not commented.

Meanwhile, national police spokesman Saleh Saaf said a team has been set up to investigate the events of last Friday.

JAKARTA URGED TO TACKLE REFUGEE CRISIS

Raymond Hall, regional representative of the U.N. High Commissioner for Refugees (UNHCR), said until now there had never been allegations of migrants being forced on to boats by police.

"There's been no suggestion people have been forced on to boats out of Indonesia. On the contrary, the suggestion has really been more that people have not been retained. People usually want to travel on," he said.

He said the UNHCR had been urging the government to tackle the refugee crisis.

Among its myriad woes, Indonesia has its hands full with some one million people already internally displaced by separatist and communal fighting along the country's outer reaches.

Middle Eastern and Afghani immigrants usually reach Indonesia via Malaysia and wait for years to get on rickety fishing boats paying around $1,000 a head to people smuggling syndicates.

Underscoring the potential for further disaster, police in the West Timor town of Kupang have rounded up around 200 mostly Afghani asylum seekers whose boat ran aground at the weekend on the remote eastern island of Rote.

And another boatload of more than 200 asylum seekers arrived at Australia's Ashmore Reef in the past day or so despite being warned off by the navy, the Australian Associated Press reported from Sydney.