Zimbabwe President Robert Mugabe said he was "very hopeful" that a breakthrough would be reached on Wednesday in power-sharing talks with the opposition.

The 84-year-old president arrived nearly two hours late for a second day of talks with opposition leader Morgan Tsvangirai on rescuing a flagging deal to form a unity government.

Former South African leader Thabo Mbeki is mediating the talks aimed at saving the month-old pact that he brokered among the bitter rivals.

Asked as he entered the talks if he was hopeful that a deal would be reached on Wednesday, Mugabe said, "Very hopeful."

Under the deal, Mugabe would remain as president while Tsvangirai takes the new post of prime minister.

But Tsvangirai has threatened to pull out of the pact after Mugabe announced last weekend that he would give his own party the most important portfolios.

AFP