Four top Belarus officials have been banned from entering the European Union and the US, in protest at a crackdown on dissidents.
President Lukashenko is widely accused of human rights abuses
The EU says Belarus failed to investigate the disappearances of three opposition politicians and a journalist between 1999 and 2000.
The EU asked for the inquiry in May, after a report by the Council of Europe, which campaigns for democracy.
Those banned include the interior minister and the sports minister.
An EU spokesman named the four officials as: Interior Minister Vladimir Naumov, Prosecutor-General Victor Sheyman, Sports Minister Yuri Sivakov, and a high-ranking officer of the special forces, Colonel Pavlichenko.
The US State Department said it would take steps "to ensure that Belarusian officials implicated in these politically motivated disappearances will not be able to travel freely to the United States".
State Department spokesman Adam Ereli urged Belarus to "provide a
full accounting of these disappearances and the ensuing cover-up, and to hold the perpetrators immediately accountable".
Earlier this year the Council of Europe published a damning report on the disappearances, accusing the Belarusian authorities of a cover-up.
Following forensic-style analysis of what little evidence was available, author Christos Pourgourides concluded that "steps were taken at the highest level" to conceal the truth.
The Pourgourides document accused Belarus officials of being behind the disappearances between May 1999 and July 2000 of former Interior Minister Yuri Zakharenko, former Prime Minister Viktor Gonchar, former electoral commission chairman Anatoly Krasovski and journalist Dimitri Zavadski.