Johannesburg/Harare- Former South African president Thabo Mbeki was due to return to Zimbabwe Monday to try to salvage the power-sharing deal he clinched a month ago between die-hard President Robert Mugabe and his arch-rival Morgan Tsvangirai.

Mbeki's spokesman told SAPA news agency he would travel to Zimbabwe Monday afternoon at the behest of "all the parties in Zimbabwe plus SADC (the Southern African Development Community, which deployed him as Zimbabwean mediator last year)."

Mbeki's new round of mediation comes a day after Movement for Democratic Change (MDC) leader Tsvangirai warned Sunday his party would pull out of the September 15 unity deal unless Mugabe's Zanu-PF relaxed its position in ongoing negotiations.

The MDC and Zanu-PF are at loggerheads over the distribution of ministries in the unity government, in which Zanu-PF is to get 15 of 31 ministries and the MDC 16 - 13 for the majority MDC faction led by Tsvangirai and 3 for a splinter faction led by Arthur Mutambara.

After failing to agree with the MDC on who should get which ministry, Mugabe at the weekend unilaterally awarded his party control of defence, foreign affairs and home affairs, among other portfolios.

Expressing outrage at the move, Tsvangirai, who is supposed to become prime minister, told a rally Sunday his party would be obliged to pull out of the deal if the MDC did not gain control of home affairs.

Whoever controls home affairs controls the police. Mugabe has used the army and police against the MDC for years.

The MDC had implored Mbeki to return to try to break the logjam but Zanu-PF had initially resisted, saying it saw no need.

Power-sharing is seen as the only possible panacea to Zimbabwe's acute economic crisis.

Over 2 million people in the once-bountiful country need food aid as a result of 84-year-old Mugabe's populist policies, which have sent inflation soaring to over 200 million per cent, one of the highest levels on record.

Western governments have pledged to plough aid and investment into the country, but only if an MDC-dominated government is installed. (dpa)