Australia said it returned 41 asylum seekers to Sri Lanka after stopping their boat, as the United Nations expressed concern over intercepting refugees at sea.

The asylum seekers, including 37 Sinhalese and 4 Tamil Sri Lankan nationals, were intercepted in waters near the Cocos Islands in late June and transfered to authorities outside the city of Batticaloa yesterday, Immigration Minister Scott Morrison said in a statement today.

They were part of a “maritime people smuggling venture,” he said.

Prime Minister Tony Abbott’s coalition says it’s fulfilling a pre-election commitment to “stop the boats” amid hundreds of deaths at sea and an influx of refugees under the previous government.

Australia has previously criticized human rights violations in Sri Lanka, and the opposition Greens Party said today the government wasn’t fulfilling its international obligations.

 “There is nothing legal about what the government is doing out on the high seas,” Greens Senator Sarah Hanson-Young said in a statement. The UN has confirmed the government’s actions don’t accord with Australia’s legal obligations, she said.