Ten U.S. diplomats were ordered to leave Belarus within 72 hours on Wednesday, intensifying a row over sanctions and human rights.
U.S. charge d'affaires Jonathan Moore, speaking to reporters after being summoned to the Foreign Ministry, said the U.S. Embassy would abide by orders from the ex-Soviet state's authorities.
Belarussian President Alexander Lukashenko, in power since 1994, has long been accused of crushing freedom of speech and assembly. He has been barred from both the United States and European Union on allegations he rigged his 2006 re-election.
Moore said he believed new sanctions would be introduced if Belarus did not release all detainees deemed to be political prisoners. "Yes. I believe it will be soon," he said.
Belarussian authorities said Washington had failed to comply with a demand to reduce its embassy's staff, the second this year.
"The Foreign Ministry provided a list of 10 diplomats which must leave the country in the course of 72 hours," Moore said. He said 15 diplomats were now in Minsk.
"We will do everything possible so that the U.S. diplomats leave the country within the required time limit."
The Foreign Ministry said earlier that it had issued a list of U.S. diplomats it said had to leave over Washington's failure to cut staff at its embassy.
The ministry's Web site said a note had been issued to Moore over the demand to reduce embassy staff from 17 to six. The U.S. ambassador left the country last month at the urging of authorities and another diplomat had also gone.
Focus on detained academic
U.S. officials have said a resumption of dialogue is possible only if Belarus releases its most prominent detainee, academic Alexander Kozulin, jailed for 5 1/2 years for helping stage mass protests against the president's re-election.
Lukashenko ruled out any release of Kozulin on Tuesday in his annual state of the nation address to parliament.
Kozulin turned down an offer last year to go to Germany for treatment of his ailing wife on the grounds it amounted to going into exile. His wife has since died.
The reductions in staff had had been sought in connection with what authorities said were extensions of U.S. sanctions.
The ex-Soviet state has been particularly unhappy about sanctions against oil products company Belneftekhim.
It accused Washington of extending punitive measures against the firm, which accounts for about a third of Belarus' foreign currency earnings and asked U.S. ambassador Karen Stewart to leave the country last month.
Washington denied there had been any such extension.
After quarrelling with traditional ally Russia last year over energy prices, Lukashenko tried to improve ties with the West, particularly the European Union.
The United States and the EU denounced the jailing last week of two activists who took part in a January protest on the grounds they had assaulted security forces.
