Zimbabwe's ruling party and the opposition are close to a power-sharing deal that would turn Robert Mugabe into a ceremonial president, a South African newspaper reported on Tuesday.

The report came as Zimbabwean state media reported ZANU-PF and the opposition Movement for Democratic Change had agreed to expand their negotiating teams in a move the ruling party called a "good omen".

"They are down to detail now," The Star newspaper quoted one source as saying. "Although how long that will take is still unclear. But a deal is not far off. Not at all."

South African President Thabo Mbeki has been mediating between the rival Zimbabwean parties since last year.