The Bush administration says it is more than doubling emergency U.S. aid to Zimbabwe to combat a cholera epidemic it blames on the government of President Robert Mugabe.  U.S. officials are trying to increase international pressure on Mr. Mugabe to step aside. 

The Bush administration is coupling its announcement of more aid to Zimbabwe with an escalation of its criticism of Mr. Mugabe, who it accuses of transforming Zimbabwe into a failed state.

At a State Department news conference, the administrator of the U.S. Agency for International Development, Henrietta Fore, said the United States is committing another $6.2 million in emergency aid to battle the cholera outbreak, on top of $4.6 million already provided.

Fore said the cholera epidemic cannot be separated from the economic crisis in Zimbabwe stemming from years of misrule by Mr. Mugabe and the political stalemate stemming from this year's disputed elections.

"Over the years, Zimbabwe's health system has deteriorated, and infrastructure has collapsed. Poor water and sanitation systems, coupled with increasingly-inaccessible health and other services have caused the cholera outbreak in Zimbabwe. This outbreak is a breakdown of Zimbabwe's government services, pure and simple," she said.

The aid official said the new aid will focus on water, sanitation and hygiene programs and supplies, and that a team of U.S. disaster relief experts has been sent to Zimbabwe to coordinate the delivery of the assistance and assess further needs.

Fore was joined at the press event by U.S. ambassador to Zimbabwe James McGee, who is in Washington to receive a State Department Human Rights Week award for rights advocacy in Zimbabwe.

McGee said the Zimbabwean president and cronies, who have rebuffed international calls for power-sharing with the opposition, are holding Zimbabwe hostage and said the once-prosperous country is rapidly deteriorating into what he termed failed state status.

The outspoken U.S. envoy said he believes calls by President Bush, British Prime Minister Gordon Brown, French President Nikolas Sarkozy and other world leaders for Mr. Mugabe to step down are beginning to have tangible effects, despite his defiant stance.

"They have all said in the last week that it is time for Mugabe to go, and I think that what we are seeing right now with this continued man-made humanitarian crisis is that they are absolutely correct.  It is time for Mugabe to go.  He has outlived his usefulness in Zimbabwe," Mr. McGee said.

Ambassador McGee said human rights in Zimbabwe continue to deteriorate in tandem with health conditions, and listed the cases of more than 20 opposition activists who have disappeared - apparently abducted by government agents - in recent weeks.

But the Mugabe government was not accused of trying to impede the work of U.S. and other relief workers dealing with the cholera outbreak.  USAID administrator Fore says beleaguered Zimbabwean health officials are working as partners.

Despite its sharp political differences with the Mugabe government, the Bush administration has continued humanitarian aid to Zimbabwe, which during the past year exceeds $250 million.