People clamber on the rocky shore on Christmas Island during a rescue attempt as a boat breaks up in the background Wednesday. ((ABC/Associated Press))

A wooden boat carrying a group of asylum seekers has smashed apart on jagged rocks in heavy seas off an Australian island, killing at least 28 people.

The boat, which was believed to be carrying as many as 100 people, crashed off the shore of Christmas Island, a remote island in the Indian Ocean.

Australian officials said Wednesday that 28 bodies were recovered from the water. Forty-four others were rescued from the water, while one person made it to shore.

The search for survivors will go on until last light and officials said they will then decide whether to continue the search into the night, the Australian Broadcasting Corporation reported.

Many people on Christmas Island watched helplessly from the top of a cliff as the boat broke apart in the pounding surf.

"The conditions were so severe, you could not really see people clearly, you could just see them being thrown around like rag dolls," said Philip Stewart, who was on the island making a documentary film.

He watched as six survivors clung to part of the battered boat.

"The woman disappeared, the child disappeared and one by one the others disappeared as well," he said.

People tossed life-jackets and ropes to people into the water, but the surf was so powerful that even two inflatable rescue boats sent by Australian officials couldn't get close to the people in the water.

The Royal Flying Doctor Service (RFDS) sent doctors to the island to help treat patients, said Joeley Pettit-Scott, the group's spokeswoman.

Most of the passengers who were rescued had moderate injuries, while three people had more severe injuries — including head injuries and abdominal trauma, the Australian Broadcasting Corporation reported.

It was not immediately clear where the passengers were from, but in recent years, many asylum seekers have headed to Australia from Afghanistan, Iran and Iraq. Generally, they first fly to Indonesia and then continue to Australia in cramped, barely seaworthy boats.

Many of the asylum seekers are housed in a detention centre on Christmas Island, which is closer to Indonesia than Australia.

"It's a controversial issue, because asylum seekers can be kept in detention for years without knowing when — or even if — they'll have their asylum claims accepted," reporter Peter Hadfield said from Sydney.

Women, children screamed for help

Photos and videos taken by witnesses at the scene show the wooden boat crashing into the rocks and breaking apart. The images also show people floating in the water amid the wreckage. It is unclear if they are alive or dead. The boat was about six to nine metres long, with a cabin covered by a sheet of fabric or plastic.

A boat loaded with asylum seekers approaches the rocky shore of Christmas Island, just before breaking up on the rocks Wednesday. ((ABC/Associated Press) )

Resident Michael Foster watched in horror as women and children screamed out for help in the churning seas below.

"They had life-jackets on them, but the water was just pushing them up ... and throwing them towards the rocks," Foster told the AP. "It was a pretty horrible situation."

The Australian Federal Police would only say that they had responded to a "maritime incident" involving a suspected illegal vessel on the island. The department declined to comment further.

Navy and customs vessels were on the other side of the island helping another boat of asylum seekers in calmer seas and took a while to respond to the calls for help, according to Simon Prince, who lives near the cliff where the boat crashed.

"Eventually the navy did come around and start picking people out of the water but it was too late for some," Prince said.

Prime Minister Julia Gillard cut short her holiday to return to Canberra after the boat crashed, the Australian Broadcasting Corporation said.