Updated

Police stormed the offices of Zimbabwe's main opposition party Wednesday and arrested its leader hours before he planned to talk to reporters about a wave of political violence that had left him briefly hospitalized.

Party head Morgan Tsvangirai was taken along with other political opponents of President Robert Mugabe in a bus to an undisclosed location by officers who had sealed off approaches to his headquarters and fired tear gas to drive away onlookers, the party and witnesses said.

The Movement for Democratic Change said Tsvangirai had been scheduled to give a press conference on President Robert Mugabe's government's escalating violence against and intimidation of political opponents.

"Tsvangirai and a number of others we have not been able to identify have been taken by police in a bus. We don't know their whereabouts. We don't know if they have been charged," said Eliphas Mukonoweshuro, an aide to Tsvangirai.

Mukonoweshuro said police had searched the offices of Harvest House, the opposition headquarters in downtown Harare, after sealing off the building and two nearby streets and firing tear gas.

Also Wednesday, Mukonoweshuro reported a series of mysterious assaults on party officials. He said one, Last Maengahama, was abducted Tuesday by unidentified assailants after a memorial service for an activist killed during the March 11 unrest.

Maengahama was taken to a small town in northeastern Zimbabwe, stripped and dumped in the bush, Mukonoweshuro said. He managed to borrow some clothes Wednesday and make his way into a town where he phoned for help.

Mukonoweshuro said the party was now investigating reports that three other officials were also abducted Tuesday night.

The European Union said it viewed Wednesday's arrest of Tsvangirai with "great concern," said Jens Ploetner, a spokesman for the Foreign Ministry of EU president Germany.

Tsvangirai, 54, also was arrested along with about 50 other people on March 11 as opposition, church, student and civic groups tried to stage a prayer meeting. Supporters said police smashed his head against a wall repeatedly. He suffered deep lacerations and swelling.

He left the hospital in a wheelchair on March 16.

"The EU president holds the leadership of Zimbabwe responsible for the bodily injury to Tsvangirai and calls for him to have immediate access to legal, and if necessary, medical consultation," Ploetner said.

Mugabe, 83, who has vowed to crush opposition to his rule, was to attend an emergency meeting of Southern African leaders in Tanzania Wednesday focusing on the political turmoil in his country. Mugabe has led Zimbabwe since independence from Britain in 1980.

The crisis of governance and high-level corruption has led to an economic meltdown, with record inflation of 1,700 percent, the highest in the world, and acute shortages of food, hard currency, gasoline and essential imports.

The Zimbabwe Congress of Trade Unions, which is linked to the opposition, has called for a national protest strike in early April, ahead of Zimbabwe's 27th anniversary of independence.

Tsvangirai said Tuesday he would boycott presidential elections scheduled next year unless the poll is carried out under a new democratic constitution that ensures they are free and fair.

"We will never go into an election that is predetermined," Tsvangirai said at a memorial service for Gift Tandare, 31, who was shot and killed at the March 11 prayer meeting.

Tsvangirai told about 800 mourners there was no going back on a campaign of protests to demand reform and pressure Mugabe to step down.

"We will not betray Gift and the people who have sacrificed themselves for the people of this country," he said.

Zimbabwe's Roman Catholic bishops said Tuesday that the political and economic crisis in Zimbabwe had reached a flash point and further bloodshed and a mass uprising could only be averted by democratic reforms.

"As the suffering population becomes more insistent, generating more and more pressure through boycotts, strikes, demonstrations and uprisings, the state responds with ever harsher oppression through arrests, detentions, banning orders, beatings and torture," the Zimbabwe Catholic Bishops Conference said in an Easter pastoral letter.

The pastoral message, titled "God Hears the Cry of the Oppressed," follows criticism that Catholic leaders have sat not done enough to pressure Mugabe, a Catholic, to halt worsening poverty and stem human rights violations.