Leading article: Beware a despot bearing gifts of shared power

The negotiations over Zimbabwe's political future have entered a sensitive and treacherous new phase. Many expected a power-sharing deal to be announced at the beginning of the week. But the leader of the Movement for Democratic Change (MDC), Morgan Tsvangirai, has called a halt to the negotiations, amid rumours of a split in the opposition. Arthur Mutambara, the leader of a breakaway faction of the MDC, has been accused of doing an unofficial deal with President Robert Mugabe, heaping the pressure on Mr Tsvangirai to sign up to the offer on the table.

Yet Mr Tsvangirai is right to resist this pressure. It is important to remember that the MDC leader enjoys more political legitimacy than Mr Mugabe in Zimbabwe. Mr Tsvangirai defeated Mr Mugabe in the first round of the presidential elections in March. And he would almost certainly have done so again in the June run-off had it not been for a vile campaign of violence against MDC supporters by Mr Mugabe's thugs, which forced Mr Tsvangirai to withdraw. The MDC also won the most seats in the parliamentary elections earlier this year. Mr Tsvangirai should not allow himself to be bounced into signing anything. Moreover, there is a grave danger lurking in any power-sharing agreement. In 1987, Mr Mugabe entered a coalition with his great rival, Joshua Nkomo. It did not take very long for Mr Mugabe to turn Mr Nkomo into a political irrelevance. The Zimbabwean President, doubtless, hopes to perform the same trick again.

The temporary confiscation yesterday of Mr Tsvangirai's passport by state officials as the MDC leader was on his way to the Southern African Development Committee's meeting in Johannesburg tomorrow is a clear sign that Mr Mugabe has not changed. He still regards the MDC as impudent upstarts, to be harassed and bullied at every available opportunity.

Reports from the talks suggest that the proposed deal would make Mr Mugabe "founding president" and Mr Tsvangirai prime minister. But the opposition should not be taken in by such cheap symbolism. The critical question is who would have control over the state's instruments of violence. If Mr Mugabe retains control over the military and the police, it would be a disaster for the people of Zimbabwe. He would continue to use that power base to terrorise opponents and subvert the democratic process. Of course, if Mr Tsvangirai gained control over the economy that would be no small prize, especially if European Union and United States aid is delivered. But the real key is executive power over the security services. The only deal that Mr Tsvangirai should accept is one that allows him to call fresh elections within a reasonable period and also enables the MDC leader to bring under control the country's military and police chiefs.

Can he realistically secure such a deal? Strengthening Mr Tsvangirai's hand is the fact that the international aid Zimbabwe's basket-case economy so badly needs will only be delivered if he is given real power; but weakening it is the fact that the South African President, Thabo Mbeki, is in charge of the mediation process. Mr Mbeki is fatally compromised by his historic ties with Mr Mugabe and his personal dislike for Mr Tsvangirai. This bias is emerging as the main obstacle to progress.

The African heads of state attending the SADC meeting tomorrow should call on the mediation committee to be widened to counterbalance Mr Mbeki's influence. If Zimbabwe is to emerge from its prolonged nightmare, what it needs more than anything is an honest broker.