A White House spokesman Thursday said the United States is coordinating its response -- including possible added sanctions -- with the European Union and a number of African governments. The new sanctions would include a freeze on assets kept in the United States by the Zimbabwean leadership.

The spokesman said those African countries that have defended the legitimacy of the Zimbabwe elections are sending a negative signal to the rest of the world about Africa's commitment to the rule of law and democracy.

Earlier Thursday, Zimbabwe's former colonial power, Britain said it refused to recognize Mr. Mugabe's re-election. Foreign Secretary Jack Straw said Zimbabwean voters were plainly denied their fundamental right to choose their leader.

A Commonwealth observer group has issued a negative report, which could lead to Zimbabwe's ejection from that organization of countries with historic ties to Britain. Germany's cooperation minister has told a Frankfurt newspaper her government may suspend its aid to Zimbabwe.

Official results show President Mugabe defeating Mr. Tsvangirai, 55 to 40 percent. Mr. Tsvangirai has rejected the count, saying it is the result of massive fraud.