The Christmas Island immigration detention camp, south of Jakarta, Indonesia, was a favorite target of people smugglers who brought asylum seekers from Asia, Africa and the Middle East in rickety boats from Indonesian ports before the trade virtually stopped in recent years.

Prime Minister Scott Morrison said a security committee of his cabinet agreed to reopen the camp on the advice of senior security officials.

The decision was made before the Senate passed legislation 36 votes to 34 that would allow doctors instead of bureaucrats to decide which asylum seekers on camps on the Pacific island nations of Papua New Guinea and Nauru can fly to Australia for hospital treatment.

Morrison's conservative government argues that the bill, passed 75 to 74 by the House of Representatives on Tuesday, will undermine Australia's tough refugee policy. The policy banishes asylum seekers who attempt to reach Australia by boat to the Pacific island camps in a bid to deter other asylum seekers from making the perilous voyage.

"My job now is to ensure that the boats don't come," Morrison told reporters. "My job now is to do everything in my power and the power of the government to ensure what the Parliament has done to weaken our border does not result in boats coming to Australia."

The legislation demonstrates the government's weak hold on power and will put asylum seeker policy at the forefront of campaigning ahead of elections that Morrison wants to hold in May. He has ruled out calling a snap election on the refugee issue.

Morrison said he would repeal the "foolish law" if his government were re-elected.

Australian governments rarely lose votes in the House of Representatives, where parties need a majority to form an administration.

Legislation has only been passed in the House against a government's will in 1929, 1941, 1962 and 2013.

The ruling coalition lost its single-seat majority when former Prime Minister Malcolm Turnbull quit politics after he was deposed by his party colleagues in August. Another lawmaker has since quit the government as part of the bitter fallout over the leadership change.

Refugee advocates applaud the law that they regard as a more humanitarian approach toward asylum seekers.

The Senate passed similar amendments on medical evacuations despite ruling party objections on the last day Parliament sat last year.

Australian security agencies warned in December that if those amendments became law, asylum seekers would likely head to Australia again in significant numbers.

The people smuggling boat traffic has all but stopped in the past five years with the government promising that any refugees who arrive on Australian shores by boat will never be allowed to settle there.

Opposition leader Bill Shorten on Tuesday re-drafted the amendments passed by the Senate in December in an attempt to make the law less likely to attract a new wave of asylum seekers, who used to arrive in Australia at a rate of more than a boat a day.

The changes included a provision that only the 1,000 asylum seekers currently held on Nauru and Papua New Guinea and not any future arrivals would be considered for medical evacuation under the new regime.

The government had struck a deal in 2016 for the United States to accept up to 1,250 refugees languishing on Nauru and Papua New Guinea. The government had similarly made the offer only available to refugees on the islands at the time to avoid attracting new asylum seekers, Shorten said.

"I believe that we can keep our borders secure, we can uphold national security but still treat people humanely," Shorten told Parliament.

Refugee advocates and lawyers had lobbied senators to back the amendments passed by the House. They said delays in medical treatment had cost asylum seekers' lives and left others at risk of blindness or kidney failure. Rape victims had endured traumatic late-term abortions.

"Yesterday was a victory for the conscience of this nation," Asylum Seeker Resource Center chief executive Kon Karapanagiotidis said of the House vote.

"Yesterday was a win for compassion and decency over the politics of fearmongering and hysteria and cruelty that we have seen under this government," he added.

Medical evacuations have become a loophole in Australia's policy of exiling asylum seekers who arrive by boat.

Hundreds of asylum seekers who have been allowed into Australia for hospital treatment have received court injunctions that prevent their return to the islands.

Sick asylum seekers often have to fight the Australian government in court for permission to be transferred to an Australian hospital.

The sprawling Christmas Island camp was closed in October and is one of 19 immigration detention centers that the government closed due to an absence of boat arrivals.

The government said at the time the Christmas Island facilities would be "kept in a state of operational readiness" so that they could be reopened at short notice.

The center was completed in 2008 with a capacity of fewer than 2,000 inmates, but by 2013 held almost 3,000 asylum seekers due to a surge in boats.

The center on Australian territory has been the scene of violent riots, hunger strikes and numerous incidents of self-harm. A wooden boat carrying 90 asylum seekers from Iran and Iraq ran onto rocks on Christmas Island in 2010, killing 48.

Because it was the most prison-like of Australia's immigration centers, Christmas Island had been repurposed in recently years to house foreign criminals who had completed sentences in Australian jails and were fighting deportation. But 17 Vietnamese asylum seekers who reached northeast Australia in August last year — the first boat arrival in four years — were sent to Christmas Island before they were returned to their homeland.

Home Affairs Minister Peter Dutton said part of the Christmas Island facilities "can be opened very quickly." Dutton did not say what category of asylum seeker might be sent to Christmas Island instead of Nauru.

"There is no question that people smugglers will be hearing very clearly that the policy in Australia has changed," Dutton said. "This puts Australia back on the map for people smugglers and Bill Shorten has that on his shoulders."