Australian authorities suspended an air and sea search Wednesday for nine people still missing from a boat that sank last weekend with suspected asylum seekers aboard in a remote part of the Indian Ocean.

Home Affairs Minister Brendan O'Connor said in a statement that medical advice indicated there was no chance of remaining survivors from Sunday's disaster. Most of the passengers were from Sri Lanka.

A search effort involving vessels and aircraft from Japan, Taiwan and Australia rescued 27 survivors from the sea in the days after the vessel sank. One body was also recovered, while two bodies were sighted but not retrieved. Nine others remained missing.

"This is a tragic incident," O'Connor said.

The survivors are being taken to Christmas Island, an Australian territory where asylum seekers are processed, for medical checks.

"They will receive appropriate medical treatment and mental health support, including grief counseling," O'Connor said. "Their health and well-being is our first priority."

He said the passengers' reasons for traveling at sea would be investigated later. Some aspects of the emergency — such as an unseaworthy boat carrying so many people in waters sometimes used by human traffickers — signaled that they are likely asylum seekers.

The boat went down late Sunday about 400 miles from the Cocos Islands, sparsely populated atolls about 1,500 miles northwest of the Australian coast and about 800 miles south of Indonesia.

The boat was in international waters but within Australia's area of responsibility for search and rescue operations.

There has been a surge of boats carrying asylum seekers toward Australia, with 37 boats carrying about 1,800 asylum seekers arriving in Australian waters this year.

Many of the people — usually from Iraq, Afghanistan or Sri Lanka — pay thousands of dollars to people smugglers who send them to sea in leaky boats from Indonesia and sail south. Most are caught by customs authorities and are detained in an immigration camp on remote Christmas Island while their refugee applications are assessed, a process that can take months or years.