The new attorney-general of the Solomon Islands has been arrested in Papua New Guinea and faces extradition to Australia on a child-sex charge.
Solomons' PM Manasseh Sogavare has been in dispute with Australia
Julian Moti, an Australian citizen of Fijian descent, was appointed to his new post just last week.
Correspondents say the arrest is likely to further strain already poor ties between Australia and the Solomons.
Solomons' Prime Minister Manasseh Sogavare recently expelled Australia's most senior diplomat.
Mr Sogavare came to power after riots in the Solomon Islands earlier this year.
He recently accused Australia of "heavy-handed" interference in the Solomons' domestic affairs.
Australia has deployed security forces in the Solomons since 2003, when it was invited there by the government to restore order after the country came close to collapse.
Australian Justice Minister Chris Ellison said Canberra would "seek Mr Moti's extradition from Papua New Guinea to face prosecution in Australia for an alleged child-sex offence".
"The Australian government attaches the utmost importance to ensure that persons facing such allegations are brought to trial in Australia," he said.
Mr Moti is thought by Canberra to have encouraged Mr Sogavare to set up an inquiry into April's riots, the Australian Associated Press news agency reports.
Critics accuse the prime minister of initiating the police investigation to clear two lawmaker allies who were charged with inciting the riots.
Mr Sogavare expelled Australia's chief envoy over Canberra's accusations.