Zimbabwean Prime Minister Morgan Tsvangirai has accused President Robert Mugabe of violating the constitution and of unilateral decision-making.
Mr Tsvangirai said his MDC party would not recognise any key appointments made by Mr Mugabe in the past 18 months, including governors, judges and envoys.
He also urged the international community to do the same.
Mr Tsvangirai formed a power-sharing government with bitter rival Mr Mugabe in 2009 after disputed elections.
Under their coalition deal, the two politicians agreed to draw up a new constitution followed by a referendum and then fresh elections.
"We will refuse to recognise any of the appointments which the president has made illegally and unconstitutionally over the last 18 months," Mr Tsvangirai said at a news conference in Harare on Thursday.
He said the disputed appointments included the central bank governor, the attorney general, five judges, six ambassadors and the police commission.
Mr Tsvangirai also voiced his "disgust" over Mr Mugabe's unilateral decision to re-appoint 10 provincial governors last week.
"I have defended President Robert Mugabe at my own cost politically. But neither I nor the MDC can stand back any longer and just allow President Mugabe and the Zanu-PF to defy the law, to flaunt the constitution, and to act as if they own this country," he said.
The MDC (Movement for Democratic Change) leader also accused the president of refusing to swear in white farmer Roy Bennett, the prime minister's choice for the post of deputy agriculture minister.
Mr Bennett was tried earlier this year on charges of plotting to oust Mr Mugabe and found not guilty.
"The matter of Roy Bennett has now become a personal vendetta and part of a racist agenda," Mr Tsvangirai said.
Neither President Mugabe nor his Zanu-PF have publicly responded to Mr Tsvangirai's comments.