State Department spokesman Sean McCormack said the diplomats in Minsk were told they had 72 hours to leave Belarus. About four people will be left at the mission, he said.

"We told the Belarusians in private and we will say in public that we believe that this action is unjustified and unwarranted," McCormack said during a news briefing. "(We) are considering what our response will be."

The expulsion comes after the United States imposed sanctions because of the authoritarian rule of President Alexander Lukashenko, The Washington Post said. After the 2006 presidential election independent observers said was fraudulent, Lukashenko and other Belarusian officials were barred from traveling to the United States and the European Union.

The United States also imposed sanctions on the Belarusian state oil company, saying Lukashenko controlled it.

U.S. Ambassador to Belarus Karen Stewart was ordered to leave in March.

The United States wants a good relationship with Belarus, McCormack said, but not at the expense "freedom of expression, political freedoms ... and other freedoms in Belarus."