In a statement, Bush said Friday's presidential election was a "sham," CNN reported. The opposition leader, Morgan Tsvangirai, who outpolled Mugabe in the initial election March 29, dropped out of the runoff, saying violence and intimidation by Mugabe's Zanu-PF Party had made a fair vote impossible.

"I am instructing the secretaries of State and Treasury to develop sanctions against this illegitimate government of Zimbabwe and those who support it," Bush said. "We will press for strong action by the United Nations, including an arms embargo on Zimbabwe and travel ban on regime officials."

Bright Matonga, a spokesman for the government of Zimbabwe, said the United States and Britain should treat the country as a partner.

Zimbabwe's economy has been in a freefall for several years with inflation so drastic it is almost impossible to measure, so it is not clear how effective new sanctions can be.