Australian opposition parties have accused the government there of using its foreign aid budget to pay Cambodia to resettle refugees that have sought asylum in Australia.

Senators from the Labor and Greens parties interrogated Attorney-General George Brandis at a hearing on Wednesday, accusing the government of using foreign aid as a “slush fund” for the refugee scheme, Fairfax media reported.

According to the Greens, Australian Foreign Ministry officials have confirmed that a $370 million increase to “cross-regional programs” in the foreign aid budget could be used to pay for the scheme.

“The Abbott Government is staying silent about this money for now, but it’s certainly an extraordinary coincidence,” Greens Senator Sarah Hanson-Young said in an email.

Brandis took the questions “on notice” at the hearing. Officials with Australia's Department of Foreign Affairs and Trade could not be reached.