Zimbabwe opposition leader Morgan Tsvangirai has called for fresh elections, supervised by international observers, if deadlocked power-sharing talks do not reach a breakthrough.

With South African president Thabo Mbeki expected in Harare later this week in a bid to revive the negotiations, Tsvangirai told thousands of supporters he would only sign a deal that gives him "sufficient" power.

"If there are continued problems over the presidency, then we go for national elections supervised by the international community," he told a rally marking the ninth anniversary of the creation of his Movement for Democratic Change (MDC) party.

Talks in deadlock

Talks between President Robert Mugabe and Tsvangirai, whose MDC holds a parliamentary majority, deadlocked in mid-August over Mugabe's desire to retain control of the security forces, according to the opposition.

The talks are being brokered by Mbeki on behalf of the Southern African Development Community (SADC), a 15-nation bloc.

Mbeki's expected trip to Harare this week comes after Mugabe threatened to form a cabinet if Tsvangirai delayed signing a document to pave the way for a power-sharing deal.

"Mugabe should be head of state and I head of government," Tsvangirai told the rally in Gweru, about 275km southwest of the capital, Harare, with about 6,000 supporters in attendance.

"If he does not accept that, let it be. We have time on our hands and we have the people on our side... We would rather have no deal than a bad deal."

MDC supporters gathered at the rally openly wore MDC T-shirts emblazoned with Tsvangirai's face.

Crackdown on MDC rallies

Such scenes were rare in the run up to Zimbabwe's June presidential run-off, when authorities barred opposition rallies and detained Tsvangirai several times as he sought to campaign.

Hundreds of stick-wielding youths had gathered at the venue of the MDC's main pre-election rally on June 22 before moving on to the nearby headquarters of the ruling ZANU-PF party.

Tsvangirai announced he was boycotting the race later that day despite finishing ahead of Mugabe in the March first round, citing rising violence against his supporters.

Festive supporters

A carnival atmosphere prevailed with supporters singing and dancing.

Some carried banners with messages such as "Dialogue must respect the people's will", "Free our MPs", "Nine years fighting for better healthcare, food, jobs and education," and "We are the change you can trust".

Speaking earlier at the same rally, the MDC's second in command, Tendai Biti, recalled that the talks had stalled over powers vested in the president by the current constitution.

"The president created in this constitution is a monarch, an imperial president," said Biti, the MDC's secretary-general.

"That's the sticking point," he said. "It's the issue of the powers of the president as enshrined in this constitution that is making these talks not to move forward."

A protracted power struggle between iron-fisted Mugabe and the opposition - which shows few signs of being resolved after the president's widely condemned one-man re-election in June - has added to the country's woes.

Its economy has gone into freefall, with the world's highest inflation rate and major food shortages.

Mugabe has ruled Zimbabwe since its independence from Britain in 1980.