"The continued use of government-sponsored violence in Zimbabwe, including unwarranted arrests and intimidation of opposition figures, to prevent the Movement for Democratic Change from campaigning freely ahead of the June 27 presidential runoff election is deplorable," Bush said in a statement.

He called upon Mugabe to end the attacks and "permit freedom of assembly, freedom of speech and access to the media."

Mugabe faces a runoff with Movement for Democratic Change leader Morgan Tsvangirai June 27. Neither won a clear majority in the March 29 presidential elections.

Bush also urged the Southern African Development Community, the African Union, the United Nations and other international organizations "to blanket the country with election and human rights monitors immediately."