A high-profile Malaysian fugitive detained in Australia has created a diplomatic problem for the Australian government which cannot by law extradite someone who could face capital punishment.

Sirul Azhar Umar, a former policeman, has been sentenced to death for the murder of a Mongolian woman in 2006 after her yearlong affair with a friend of Malaysian Prime Minister Najib Razak ended in a messy disagreement.

The Australian government confirmed Wednesday that Sirul was detained a day earlier.

Don Rothwell, an Australian National University expert on international law, says if Sirul was extradited, Malaysia would first have to ensure he would not be executed.

Malaysian Home Minister Wan Junaidi Tuanku Jaafar told the Bernama news agency that Malaysia would consider bringing legal action against Australia if Sirul was not returned.