* Doctors can no longer order evacuations of sick asylum seekers
* 500 people remain in Pacific camps, many have health issues
* Australia under pressure to clear detention centres (Adds bullet points, comment from Médecins Sans Frontières Australia in par 9, details in 12-15)
By Colin Packham
SYDNEY, Dec 4 (Reuters) - Australia on Wednesday removed the right of doctors to order sick asylum seekers be evacuated from two remote Pacific detention centres for medical treatment, a repeal that opponents said risks the lives of refugees.
Under Australia's controversial immigration policy, asylum seekers intercepted at sea are sent to camps in Papua New Guinea and Nauru. They can never settle in Australia, even if they are found to be refugees.
In February, independent lawmakers and the opposition joined forces to give doctors the right to order sick asylum seekers be sent to Australia if they required medical care.
After securing re-election in May, Prime Minister Scott Morrison said his government would seek to repeal the legislation, though he needed the support of independent lawmakers as the coalition does not enjoy a majority in Australia's upper house Senate.
After weeks of negotiations, the repeal legislation passed Australia's Senate by 37 votes to 35.
"You can take advice from doctors, but doctors aren't elected. They aren't accountable to the public," independent lawmaker Jacqui Lambie, who cast the decisive vote, told the Senate.
Around 500 people remain on the two island centres, many suffering mental health issues after more than six years in detention, aid organisations say.
The United Nations has repeatedly criticised Australia's remote detention centres, insisting they lack adequate medical and mental health care.
"To now deny medical professionals from taking decisions in patients’ best interests – and to effectively hand that power back to unqualified officials... puts those most sick and vulnerable at risk," Paul McPhun, Executive Director of Médecins Sans Frontières Australia said in a statement.
Morrison rejected those allegations, insisting Canberra has provided significant medical aid, while those unable to get necessary treatment can be sent to Australia if the minister for home affairs approves it.
As a result, Morrison said the medical evacuation legislation is unnecessary and undermines Canberra's border policy, designed to discourage asylum seekers from undertaking dangerous sea voyages to Australia.
In 2016, Australia agreed a deal with former U.S. President Barack Obama to offer refuge to up to 1,250 asylum seekers. The administration of U.S. President Donald Trump said it would only honour that deal to maintain a strong relationship with Australia, and then only on condition that refugees satisfied strict checks.
Around 650 refugees have been resettled in the United States, with a further 250 in PNG and Nauru approved to go at a future date, Peter Dutton, the Minister for Home Affairs told reporters in Canberra on Wednesday.
Australia has rejected offers from neighbouring New Zealand to take a further 150 asylum seekers, fearing refugees will use it as a 'backdoor entry' into Australia.
Media reported Lambie has sought a commitment that Canberra will now accept Wellington's offer. Morrison and Lambie declined to comment. (Reporting by Colin Packham. Editing by Lincoln Feast.)