U.S.: Zimbabwe could see 'massive starvation'

Tsvangirai, who lost a 2002 presidential election that independent observers said was rigged in Mugabe's favor, had only returned to Zimbabwe in late May to campaign for the runoff. He left the country soon after the March first round, and his party has said he was the target of a military assassination plot.

The Movement for Democratic Change says at least 60 of its supporters have been slain in the past two months.

On Thursday, a mob of Zimbabwe "war veterans," a group of often violent Mugabe loyalists, waylaid a convoy of American and British diplomats investigating political violence, beating a local staffer, slashing tires and threatening to burn the envoys, the U.S. Embassy said.

Mugabe frequently accuses Britain and the United States of plotting to topple him and return Zimbabwe to colonial rule.

Zimbabwe's social welfare minister, Nicholas Goche, sent aid groups in Zimbabwe a memorandum on Thursday ordering an indefinite suspension of field work.

Earlier this week, the aid organization CARE International said it had been ordered to halt operations pending an investigation of allegations it was campaigning for the opposition. CARE denies the allegation.

Millions of Zimbabweans depend on international groups for food and other aid as the country's economy crumbles. The world's highest inflation rate has put staples out of reach in what was once the region's breadbasket.

In London, British Development Aid Secretary Douglas Alexander said the decision was evidence of a callous contempt for human life.

"For Robert Mugabe to use the threat of hunger as a political weapon shows a callous contempt for human life," Alexander said. "For the sake of millions of the poorest and most vulnerable people in Zimbabwe, aid must be allowed to get through."

Mugabe has led Zimbabwe since independence from Britain in 1980 and was once hailed as a liberator who promoted racial reconciliation and economic empowerment.

But he has been accused of clinging to power through election fraud and intimidation, and of destroying his country's economy through the seizure of white-owned farms beginning in 2000.

More from msnbc.com Power struggle threatens Pakistan’s leader  Swine flu booster shots? Good luck with that From Levi to Letterman: Palin's rough year Obama gets mixed reviews on China's blogs Ice addict heads for poles, Everest | Trek posts On Twitter: Breaking news updates | Weird and wild

MORE FROM AFRICA

Africa Section Front

Judge tosses Rwandan genocide conviction   Kenyans recruited to fight in Somalia Cattle raiders kill at least 10 in northern Kenya Make peace — mom's dying wish to rebel leader son Tourists return to Zimbabwe as economy recovers Kenyan girls given a chance to dream Africa Section Front   Add Africa headlines to your news reader: