The move came as one of Tsvangirai’s own deputy ministers, Roy Bennett, finally appeared in court charged with plotting terrorism, insurgency and banditry, and trying to leave Zimbabwe illegally.
Bennett had been custody since being arrested hours before the new government was sworn in on Friday.
The Movement for Democratic Change described the charges as "trumped up, scandalous and politically motivated", part of "a deeper political agenda" aimed at derailing the powersharing administration agreed between the MDC and the president’s Zanu-PF.
The court is expected to rule on Wednesday on whether Bennett has a case to answer.
The unity government held its first Cabinet meeting on Tuesday, chaired by Mugabe.
According to MDC sources, the encounter was "fairly cordial" but insubstantive; Tsvangirai raised the issue of Bennett and the collapse of the rule of law more generally, but Mugabe did not address it seriously.
Afterwards, the prime minister summoned the Defence Minister, Emmerson Mnangagwa, the State Security Minister, Sydney Sekeramayi, and the Home Affairs Minister, Kembo Mohadi, to demand they observe legality.
Tsvangirai meant Bennett’s arrest and the actions of some Mugabe loyalists in blocking the release of 30 political detainees. But he also demanded an end to extra-legal moves to seize Zimbabwe’s few remaining white-owned farms.
On Monday, the attorney general, Johannes Tomana, who the prime minister wants to remove for locking up opposition activists, ordered the police to evict white farmers despite a binding ruling by a regional tribunal that the farm confiscations are illegal.
Whether the ministers act on the prime minister’s demands is an early test of his ability to assert control.
An MDC official took it as a good sign that the ministers met Tsvangirai and did not question his authority. The source said the meeting was also in part a confidence-building measure aimed at establishing a personal relationship with some of the members of the Cabinet most hostile to Tsvangirai.
The MDC leadership says it believes that once there is a return to orderly administration and the rule of law, power will seep away from the narrow band of military and senior Zanu-PF officials who have abused their positions to retain a grip on government.
However, an important step in realising that also lies in winning the confidence, or at least damping the hostility, of the military service chiefs who refused to attend the prime minister’s inauguration and who have previously threatened to take up arms against him.
Analysts say that Tsvangirai needs to assert his authority not only to ensure he can control Mugabe’s ministers, but to reassure foreign donors who have laid down rule of law and respect for property rights as a precondition for funding to revive Zimbabwe’s wrecked economy. – guardian.co.uk © Guardian News and Media 2009