"Today I have signed a new executive order that expands our sanctions against the illegitimate government of Zimbabwe," Bush said in a statement, noting the sanctions target entities and individuals linked to Mugabe's government.

"This action is a direct result of the Mugabe regime's continued politically motivated violence, disregarding calls from the Southern African Development Community, the African Union, and the United Nations to halt the attacks," he said.

The expanded sanctions are intended to add pressure on Mugabe, whose ZANU-PF hold power-sharing talks with the opposition Movement for Democratic Change after months of violence.

Mugabe scored a landslide victory in last month's election denounced by Western countries and boycotted by opposition leader Morgan Tsvangirai, who cited government-sponsored violence and intimidation.

Following Bush's executive order, the Treasury Department moved to freeze assets under U.S. jurisdiction of 17 business entities controlled by the Zimbabwe government.

It said it is banning Americans from conducting financial or commercial transactions with the entities, including the Agricultural Development Bank of Zimbabwe and manufacturers of minerals, steel, textiles, chemicals and other services.

The European Union on Tuesday expanded similar sanctions against Zimbabweans after China and Russia two weeks ago vetoed a U.S.- sponsored U.N. Security Council resolution to impose sanctions on Zimbabwe.