More than 90 per cent of boat people were found to be genuine refugees in the March quarter, figures to be released on Monday show.

But asylum seekers who arrived by plane - despite being eligible for release into the community - were almost twice as likely to be rejected as refugees.

The new figures come after the government, with Coalition support, passed its changes to the Migration Act that introduce explicit discrimination against asylum seekers based on their method of arrival.

All asylum seekers who arrive by boat will now be subject to the no-advantage rules, meaning they could face up to five years' detention in Manus Island or Nauru, and if released into the community, they would not be allowed to work for five years.

The figure for the March quarter for genuine refugees who arrive by boat - 90.5 per cent - continues a long-term trend, with 93.5 per cent of those who arrived by boat being found to be refugees in 2010-11, and 91 per cent in 2011-12.

Many asylum seekers initially given a negative assessment had their case overturned on appeal: 65.3 per cent were given primary approval for a protection visa in the March quarter.

Immigration Minister Brendan O'Connor announced on budget day that the government would commission a review of visa determinations to ensure Australia's approval rate was consistent with other countries. ''We accept that we need to abide by the [UN] refugee convention,'' he said.