Soldiers in Papua New Guinea have staged a mutiny and replaced the defence force chief, reports say.
The apparent mutiny took place early in the morning in the capital, Port Moresby, Australian media and officials said.
A group of 12 to 20 soldiers were involved, ABC News reported.
The incident appears to be linked to the conflict between Peter O'Neill and Sir Michael Somare - the two men claiming the role of prime minister.
The leader of the mutiny, retired Colonel Yaura Sasa, is a former defence attache to Indonesia.
He has declared himself commander after placing the head of the defence forces, Brigadier General Francis Agwi, under house arrest.
He has denied staging a mutiny and said instead that he was appointed by Sir Michael's government, Radio New Zealand reported.
Brig Gen Agwi backed Mr O'Neill as Papua New Guinea's prime minister.
According to the ABC report, the soldiers overpowered guards at Taurama barracks and took the commanding officer there captive.
They then moved to Murray Barracks, placing Brig Gen Agwi under house arrest.
The incident is the latest conflict in a power tussle between the two men claiming the South Pacific nation's top job.
The government voted in August last year that the post of prime minister was vacant after Sir Michael went abroad for medical treatment in March.
A Supreme Court ruling in December 2011 then stated that parliament had acted illegally by electing Mr O'Neill prime minister. The court also ruled that Sir Michael should be ''restored to the office of prime minister''.
Mr O'Neill, who is backed by the civil service and effectively running the country, refused to step down.
The Australian Department of Foreign Affairs and Trade has issued a travel advisory to ''limit travel around Port Moresby today''.
"We urge that the situation be resolved as soon as possible, and that the PNGDF chain of command is restored," the department said in a statement.
Mr O'Neill has not made any statement on the situation, the Associated Press news agency reported.
The AP also said that journalists at the country's leading Post-Courier newspaper was still ''trying to figure out exactly what has taken place''.