The Solomon Islands prime minister has ordered Australia's top diplomat on the islands to leave, raising tensions between the two countries.
Mr Sogavare became prime minister after riots in April
PM Manasseh Sogavare told Australian PM John Howard of his decision on Monday and gave High Commissioner Patrick Cole formal notice a day later.
Australia's Foreign Minister Alexander Downer said it was "outrageous".
The two sides disagree on a police inquiry Mr Sogavare has called into riots that took place in April.
The violence, which shook the capital, Honiara, erupted after an election won by the former deputy prime minister, Snyder Rini.
Parts of the capital were trashed during the riots
Thousands of anti-government protesters burned down buildings in the city's Chinese district, alleging that either China or Taiwan had paid lawmakers to vote for him.
Additional troops and police were sent to reinforce an Australian-led assistance mission already in the country to bring the violence under control.
Mr Rini resigned when several members of his government - including Mr Sogavare - defected to the opposition, and Mr Sogavare was elected prime minister.
Mr Sogavare then appointed to his cabinet two lawmakers who had been detained and charged with inciting the riots.
Critics accuse Mr Sogavare of initiating the inquiry in order to clear the two lawmakers.
"We believe that it [the inquiry] will prejudice the outcome of court cases against two imprisoned members of parliament facing riot-related allegations and it will endeavour to cast blame for the riots on the police response, including the Australian police," Mr Downer told parliament.
He later told local radio that some Solomons lawmakers were opposed to the foreign troops because they perceived them as "standing between them and the honey pot".
Australian has sent a senior diplomat, David Ritchie, to the Solomon Islands to register Australian concern at the inquiry.
Mr Downer said the decision to expel the high commissioner was "extremely unprofessional", but he said Australia would not respond in kind.
"We will take some sort of appropriate measures, but not against the generality of the people of Solomon Islands, they've suffered enough from their governments over the years," he said.