Canberra: Dozens of asylum seekers are feared dead after heavy waves smashed their timber boat onto rocks on Christmas Island in the Indian Ocean on Wednesday, sinking the boat and throwing 70 to 80 people into stormy seas.

Television footage showed the boat rammed bow first onto the rocks, splintering and sinking, and its passengers, including women and children, thrown by waves against razor-sharp rocks.

"There are people in the water crying out for help. There's a tragedy unfolding here," Christmas Island Shire president Gordon Thomson told Australian media.

Local media said 41 people had been rescued, but some 30 were still missing after the boat was destroyed around 6 a.m. (2300 GMT) local time. Australia's Flying Doctors service said the death toll could be around 50 with "about 33 walking wounded".

"We threw ropes over the cliffs and we must have thrown in a couple of hundred life jackets. About 15 or 20 people managed to get into the jackets but there are bodies all over the water," one Christmas Island resident, who wanted to remain anonymous, told the West Australian newspaper.

"There are dead babies, dead women and dead children in the water."

Western Australia state premier Colin Barnett said: "While many details about this tragedy are still unconfirmed, I understand there have been a large number of fatalities".

"Conditions in the ocean off Christmas Island are extremely dangerous," he said in a statement.

Australian Prime Minister Julia Gillard said she would return from Christmas leave to ensure she is fully briefed by on the rescue operation.

A survivor told Australian police there were some 70 to 80 people onboard the vessel, which appeared to be Indonesian. Police said they believed most passengers were Iraqis.

Christmas Island councillor Kamar Ismail said the asylum seekers appeared to be mostly of Middle Eastern origin.

"It was horrific. I saw a person dying in front of me and there was nothing we could do to save them," Ismail said.

"Babies, children maybe three or four years old, they were hanging on to bits of timber, they were screaming 'help, help, help', we were throwing life jackets out to them but many of them couldn't swim a few metres to reach them."

An Australian navy boat and a Customs vessel were helping to rescue people.

"We were awoken this morning, because our house is the first along the cliff, by screaming," said a female witness called Ingrid.

"I could hear screaming, children screaming."

"People were running around with life jackets but it was pointless because when you threw them the wind would blow them back in your face," she said.

Christmas Island, south of Indonesia, is a regular destination for refugee boats, and is home to Australia's main offshore immigration detention centre.

Rescuers said the stormy seas and Christmas Island's jagged coastline made rescuing the asylum seekers very difficult as the island has no totally protected harbour in which to land people.

"You didn't want to be anywhere closer to the cliff face because it's razor-sharp and the four-metre swells plus were throwing people around. I would suggest I saw about 30 who didn't make it," witness Michael Foster told Sky News television.