The US has ordered the expulsion of the remaining six Belarus diplomats in Washington and New York, the Associated Press news agency has said.
The United States has denied ordering Belarus to withdraw its diplomats and shut its embassy and consulate after the expulsion of 10 US diplomats.
The US is to close its own embassy in the Belarus capital Minsk, AP reports.
State department spokesman Tom Casey told reporters that while the US had "serious concerns", no decisions had been made "at this point".
Belarus has been given until 16 May to close its embassy in Washington and its consulate in New York, US officials told AP.
The Associated Press reported earlier that Washington had ordered out Belarus's last six diplomats.
On Wednesday, Belarus ordered the expulsion of 10 US diplomats as relations worsen between the countries.
It said that Belarus had been given until 16 May to shut its two missions.
The US has been critical of Belarusian President Alexander Lukashenko for his harsh treatment of opposition figures.
"At this point we have not made a decision to formally ask them [the Belarussians], or informally ask them, to reduce staff further," Mr Casey said.
"We have not made any decisions at this point."
He added that there had also been no decision to close the US embassy in Minsk.
The US has been critical of Belarussian President Alexander Lukashenko for his harsh treatment of opposition figures.
In early 2005, the US called the former Soviet republic Europe's only remaining "outpost of tyranny".
In early 2005, the US called the former Soviet republic Europe's only remaining "outpost of tyranny".
US sanctions
Reporting Mr Casey's statement, AP said the US had "abruptly backed down" on its decision to order the closure of embassy and consulate "just minutes before American diplomats were to inform Belarus of the move".
American officials said Belarus was told of the decision to expel its diplomats from the US in simultaneous meetings between representatives of the two countries in Minsk and Washington, AP reported.
It had quoted unnamed US officials as saying orders had been prepared to tell Belarus it had until May 16 to withdraw its six diplomats.
It is the latest in a string of tit-for-tat diplomatic expulsions between the two countries.
In March, Belarus ordered the US ambassador to leave.
The order was made after Washington imposed sanctions on the country's state-controlled oil-processing and chemicals company, Belneftekhim.
The firm accounts for about a third of the country's foreign currency earnings.
The US has called Belarus Europe's last "outpost of tyranny"
On Wednesday, the US was given 72 hours to send 10 of its 15 remaining diplomats in Minsk home.
The US state department called the expulsions "unjustified and unwarranted" and said it wanted good relations with Belarus.
"But we are not going to do that and sacrifice the principles of pushing for freedom of expression, political freedoms and other freedoms in Belarus," said state department spokesman Sean McCormack.
The US has been strongly critical of the human rights situation in Belarus.
The US - along with the European Union - has restricted the travel of President Lukashenko and members of his inner circle.
Both the US and the EU have demanded that Belarus frees political prisoners, and allows more democracy, before normal relations can be restored.
Earlier this week, Mr Lukashenko said the issue of freeing political prisoners was closed after the release of several detainees.
"If the Americans introduce new sanctions and think we will collapse, that's rubbish," he said.
Belarus has built close economic and diplomatic links with Russia, Venezuela, Cuba, and a number of Middle Eastern countries.
These links have kept its economy afloat despite years of condemnation from the West, says the BBC's regional analyst Steven Eke.
