Zimbabwe's opposition party leader Morgan Tsvangirai and 11 members of his presidential election campaign team were detained by police on Saturday, the Movement for Democratic Party (MDC) said.

The 12 were detained at a roadblock just outside the town of Shurugwi in the south of the country, party spokesman Nqobizitha Mlilo was quoted as saying by South Africa's Sapa news agency.

"They were taken to Shurugwi police station where they are currently being detained. At this stage we do not know the reason for their detainment," Mlilo said.

Police have detained Tsvangirai on at least four previous occasions in the last two weeks, holding him for several hours before releasing him without explanation or charge.

On Thursday, Tsvangirai was detained twice, first in the nearby town Kwekwe and later in the nearby central city of Gweru, where he had been campaigning.

Tsvangirai's deputy, Tendai Biti, meanwhile, appeared Saturday, handcuffed and in leg irons, before a judge in Harare.

The outspoken Movement for Democratic Change (MDC) party secretary general was arrested on his return to the country on Thursday after spending two months abroad in the wake of Zimbabwe's disputed general elections in March.

His whereabouts were not known a day after his arrest on Friday.

Police accuse Biti of treason - a charge that carries the death penalty on conviction - for among others allegedly illegally distributing election results.

Biti had tried to mobilize political support against the suppression of the opposition in ongoing campaigning ahead of the presidential run-off election on June 27 between Tsvangirai and incumbent Robert Mugabe.

The MDC won a majority in parliamentary elections on March 29, while Tsvangirai was accorded more votes in the simultaneous presidential election, although he failed to win more than 50 per cent which he needed to avoid fighting a run-off and to be declared outright winner. (dpa)