Boat capsizes off Christmas Island, 150 on board including women and children

The tragedy is occuring only a week after a similar disaster (pictured) where up to 90 people died.

An asylum-seeker boat carrying an estimated 150 people capsized today en route to Australia's Christmas Island, the Australian Maritime Safety Authority said.

The Australian Maritime Safety Authority (AMSA) says two merchant vessels are already on the scene.

"They are recovering survivors," AMSA spokeswoman Jo Meehan told AAP, as reports emerge seven survivors have been found.

The passengers are mostly women and children, the Daily Telegraph reports.

The asylum seeker boat's crew issued a distress call to the Australian Federal Police at 6.20am on Wednesday and the first merchant vessel arrived on the scene at about 10.30am, she said.

The navy's HMAS Maitland is expected to be on the scene by 2pm AEST and HMAS Leeuwin is due to arrive about two hours later.

A P-3 Orion plane is also on its way.

AMSA is co-ordinating the rescue even though the vessel is in Indonesia's search and rescue zone.

Australia has notified Indonesia's BASARNAS rescue organisation but it is not yet clear whether it will assist with the rescue effort.

Ms Meehan says it is too early to confirm how many people were on board the boat and how many survivors have already been rescued.

Sea conditions in the area are "fair but not ideal", she said.

Customs and Border Protection was unable to confirm the number of people on board.

"Border Protection Command has also deployed its vessels and aircraft to assist with the operation," it said in a brief statement.

"No further details are available at this time."

The capsize is the latest in a series of refugee boat disasters in recent years, as rickety, overloaded vessels packed with desperate migrants struggle to reach Australia.

Tony Abbott has told reporters in Canberra that the sinking of the second asylum seeker boat in a week was another grim day.

He says with two disasters in less than week it's important the Australian parliament does what it can to deliver a stronger policy response.

It was a "very difficult day" during which MPs should be examining their consciences, Mr Abbott said. The incident comes barely a week after another boat with around 200 people on board went down in the Indian Ocean as it made its way to Australia.

Rescuers managed to save 110 people and 17 bodies were recovered, but no other survivors have been found.

Most boats originate in Indonesia, though there has been a spike in attempts from Sri Lanka.

Though they come in relatively small numbers by global standards, asylum-seekers are a sensitive political issue in Australia, dominating 2010 elections due to a record 6,555 arrivals.

The tragedy is unfolding as more than 30 independent and cross-party MPs are meeting in a bid to force their leaders into asylum seeker reforms which could help prevent further tragedies at sea.

MPs react to reports of Christmas Island tragedy

Labor backbencher Graham Perrett said on Twitter: "150 people in the water right now. That's one for every single elected free-thinking Member of the House of Reps."

Australian Greens deputy leader Adam Bandt also tweeted "terrible reports another boat capsized".

Independent MP Craig Thomson said there was a renewed sense of urgency to resolve the issue before parliament suspended for the winter break on Thursday.

"The current impasse between the parties is not working," he told AAP.

"We should not leave Canberra until we have resolved this issue."

Opposition Leader Tony Abbott says he will attempt to introduce a draft laws to put offshore processing beyond legal doubt.

"I do think it is important particularly with two disasters in less than week that the Australian parliament do what it can to deliver a stronger policy response," he said.

Mr Abbott says his private bill, which follows a High Court decision throwing out the government's Malaysian people-swap deal, will ensure offshore processing can occur in a country that's a signatory to the UN refugee convention.

The bill will rule out Malaysia, as it is not a signatory, but allow the Nauru processing centre to be reopened.