Zimbabwe opposition leader Morgan Tsvangirai was held by police for two hours Friday, but was released without being charged. Mr. Tsvangirai, who is president of the opposition party, Movement for Democratic Change, MDC, says he was arrested for owning an unlicensed two-way portable radio.

Following his release, Mr. Tsvangirai accused Zimbabwe's president, Robert Mugabe, of setting up what he termed "institutions of violence." The MDC president said the party has been the victim of government violence, and that 83 MDC supporters have been killed as a result.

Mr. Tsvangirai said police had been what he termed "gentle" when they arrested him in a dawn raid at his home in Harare, the capital. "There were no strong arm tactics," he said.

This is the third time Mr. Tsvangirai has been arrested. On the two previous occasions, charges were also dropped, including one of treason.

President Mugabe has accused the MDC of being what he calls "a terrorist organization," and of being controlled by political forces in Britain and the United States. Mr. Mugabe has told the annual meeting of his ruling ZANU-PF party, which is being held this week, that there will be what he calls "a real physical fight" against the opposition party.

Political analysts say the Zimbabwe government is intensifying a campaign to harass and intimidate the MDC and Mr. Tsvangirai ahead of presidential elections, scheduled for March of next year.

Meanwhile, a United Nations agency, the World Food Program, has called on Western donors to give $60 million for emergency food aid for Zimbabwe. The agency says production of the staple food, maize - or corn - has dropped drastically.

Economists say the crisis has been brought about by disruption of production from invasions of commercial farms by mobs of pro-government militants, as well as by abnormal weather during the growing season.