Eight months after entering a power-sharing deal with President Robert Mugabe of Zimbabwe, Prime Minister Morgan Tsvangirai announced Friday that he and his party would boycott Cabinet meetings and withdraw from dealing with Mugabe's party, in the biggest breach yet in the transitional government. 'It is our right to disengage from a dishonest and unreliable partner,' Tsvangirai said at a news conference in Harare, Zimbabwe's capital. The catalyst for this step was the jailing on Wednesday of Roy Bennett, Tsvangirai's deputy agriculture minister-designate, a white farmer who is scheduled to stand trial Monday on three-year-old terrorism charges that his party, the Movement for Democratic Change, says are fabricated. But even after Bennett was granted bail on Friday after the news conference, officials in his party said their decision to disengage did not change. 'This is the time for us to say enough is enough,' said Thabitha Khumalo, a spokeswoman for the MDC. Tsvangirai laid out a broad array of grievances. He accused Mugabe's party, ZANU-PF, of selectively using the law to punish his legislators, putting 16,000 of its youth militia on the government payroll and remilitarizing the countryside on bases used in last year's discredited election to organize a campaign of terror against his supporters. Although he stopped short of quitting the government, Tsvangirai warned that if the crisis were not resolved and a working relationship restored, he would call for elections supervised by the United Nations. A former ZANU-PF information minister, Jonathan Moyo, who recently rejoined Mugabe's party, said Friday that the MDC's decision to disengage would reduce the party and the prime minister to political irrelevance. 'You say you've disengaged, but are not pulling out,' Moyo said. 'That's nonsensical. You're either in or out.' Tsvangirai's strategy appears to be in part an effort to get senior political leaders in the African Union and the Southern African Development Union -- guarantors of the power-sharing deal -- to pressure Mugabe to act in a more conciliatory manner. So far, regional leaders have effectively ignored Tsvangirai's pleas to step in. But the move also reflects rising anger in the ranks of the Movement for Democratic Change. Tsvangirai, who outpolled Mugabe in elections last year but withdrew from the runoff after an onslaught of attacks on his supporters, has sought to put a good face on the deal in recent months. He had argued that the country and its devastated economy had stabilized. But Bennett's jailing after uneventfully spending seven months on bail seemed to have been the breaking point for the MDC. Tsvangirai said it 'brought home the fiction of the credibility and integrity of the transitional government.' 