Ambassador James McGee said in a video conference call from the capital Harare that the humanitarian situation was "really going down the tubes" as more people went hungry, hospitals closed, the school system collapsed and cholera spread.
He said there were now 294 confirmed deaths from a cholera outbreak and a further 1,200 confirmed cases of the water-borne disease that can rapidly lead to death if not treated. Zimbabwe’s health authorities have cited a lower death toll.
"We have a very, very bad situation. I don’t see anything that will alleviate these problems until the government of Robert Mugabe starts to act in good faith," he said.
While the situation became more dire for ordinary Zimbabweans, the U.S. diplomat said Mugabe appeared to be gaining in strength as he continued to shun a September power-sharing deal with the opposition Movement for Democratic Change.
"His grip on power may be actually stronger than it was this time last year. Mugabe continues to hang on to power through the political patronage system," McGee told reporters.
"He is snubbing his nose at the international community and pretty much saying: ‘this is my country and I will do pretty much what I please,’" he added.
McGee said the U.S. strategy was to continue piling on targeted sanctions against Mugabe and his supporters and U.S. allies in Europe, Australia and elsewhere would do the same.
"We have additional sanctions that we are prepared to roll out," he said without specifying when or what these were.
McGee described a recent road trip he took through Zimbabwe’s countryside to see first-hand the "grim" situation in the rural areas.
"When you pass through villages, there is a total look of hopelessness from the people’s faces," he said.
"There are a lot of people standing around doing nothing. There are a lot of distended bellies out there of small children and people picking sweet, but non-nutritious food off trees," McGee added,
He urged the Southern African Development Community (SADC), a 15-nation regional group, to take a tougher line with Mugabe and not to treat him as president so long as he refused to accept the power-sharing deal, which is stalled over the distribution of key ministries.
"SADC needs to continue to pressure this Mugabe government to ensure that the will of the people of Zimbabwe is met," he said.
He said overall levels of violence had decreased in recent months but that there were still reports of abductions of opposition supporters, particularly in the rural areas.