"The president (Tsvangirai) has been picked up from his house 10 minutes ago," said an official from the MDC.

The charges that Tsvangirai faces were still not clear but the opposition leader had vowed at the weekend to lead the protests on Monday morning despite a high court order banning them.

The MDC blames Robert Mugabe's government for crippling economic problems and says it has popular support for the marches. Inflation is running at 269 percent and shortages of food, fuel and bank notes are causing intense hardships for Zimbabweans.

The capital, Harare, was tense on Monday, with heavily armed police and soldiers deployed on the streets.

Police have warned that anyone taking part in the protests will "face the full wrath of the law" and the government has distributed flyers urging Zimbabweans to ignore the opposition's call to demonstrate.

Riot police manned road blocks on routes leading into the city centre. All roads around Mugabe's official residence near the city centre were closed.

An eyewitness told AFP police fired teargas to break up a group of people who tried to march into the city centre from Highfield, Mugabe's home township and the nerve centre in the 1950s and 1960s of nationalist opposition to British colonial rule in the southern African country.

There were reports of beatings in some suburbs, where army and police have been patrolling since Saturday.

State radio said police were escorting state-owned passenger buses into the capital. There were very few private bus operators plying the roads.

Students at the country's main University of Zimbabwe were vacating the campus by mid-morning as tensions apparently started rising at the news of Tsvangirai's detention.