Zimbabwe's main opposition party says two campaign buses used by its presidential candidate Morgan Tsvangirai have been seized by police.
A spokesman for the Movement for Democratic Change said the move was an effort to cripple the campaign of Mr. Tsvangirai, who is facing President Robert Mugabe in runoff election June 27.
Mr. Tsvangirai was detained twice Thursday as he tried to campaign in central Zimbabwe. He was released both times after staying in police custody for several hours.
The opposition leader has now been detained four times this month
Also Thursday, police arrested the opposition party's number-two official Tendai Biti to face charges of treason - a charge that could carry the death penalty. A police spokesman, Wayne Bvudzijena, said the treason charge stems from an MDC document about changing Zimbabwe's government.
Police also wanted Biti for proclaiming an MDC victory in the March 29 presidential and parliamentary elections ahead of any official announcement.
The United States condemned the arrest and pending treason charge against Biti. The White House said it was deeply troubled by the move and called on the Security Council to take up the matter of Zimbabwe.
The MDC says supporters of President Mugabe are trying to intimidate opponents ahead of the runoff.
The MDC says ruling party supporters have killed more than 60 opposition activists since the first round of voting in March. Mr. Mugabe accuses the MDC of carrying out its own attacks.
Some information for this report was provided by AFP and Reuters.