Belarus will issue an ultimatum on Wednesday by the EU to immediately release political prisoners or face unprecedented sanctions.
By Bruno Waterfield, Brussels and Andrew Osborn in Moscow
Sergei Martynov, Belarus's foreign minister, will be told that the EU expects "the immediate release of detainees" imprisoned after a wave of beatings and arrests aimed at the opposition following presidential elections in Belarus last month.
The repression of dissent has continued in Belarus, with 21 members of the opposition still languishing in the KGB's pretrial detention centre in Minsk with little or no access to lawyers.
Charged with "organising and participating in mass riots", the detainees could face jail terms of up to 15 years each if found guilty.
In a disturbing echo of the Stalin era, fears are growing too that the authorities may try to take the young son of Andrei Sannikov, one of the country's leading opposition leaders, into care after authorities said they were investigating the boy's status. Both his parents are in jail and he is being looked after by his grandmother.
Baroness Ashton, the EU's foreign minister, will warn Mr Martynov, during talks in Brussels, that travel bans and an asset-freeze targeting Alexander Lukashenko, the Belarusian President, have already been drawn up unless the prisoners are freed.
She will also tell the regime that the EU expects a "reversal" of President Lukashenko's decisions to close down offices of the OSCE after it declared his re-election count on Dec 19 to be "bad or very bad".
European ambassadors meeting on Tuesday will agree to make "the release of political prisoners and others detained on political grounds the immediate focus of EU attention."
Sanctions, agreed in 2006 but suspended in 2008, against Mr Lukashenko and his regime can be reintroduced within days but plans "outlining a further EU response" are being drafted.
Diplomats have told The Daily Telegraph that European foreign ministers, meeting on Jan 31, will discuss extra sweeping sanctions including the withdrawal of Brussels funding, economic sanctions and a possible EU veto of IMF aid to Belarus.
"The whole relationship with Belarus is under review. The only question is how to calibrate sanctions against the regime so the ordinary population of Belarus don't pay," said a diplomat.