Lithuania has expelled three Russian diplomats on suspicion of espionage.
President Rolandas Paksas denies wrongdoing
It said they had been illegally trying to influence privatisation and obtain information from parliament about allegations against the president.
The move comes as Lithuanian President Rolandas Paksas faces impeachment over his alleged links with Russian criminals - claims he denies.
Correspondents say it is not clear if the deportations have any connection with the case against Mr Paksas.
"I can confirm with regret the fact that three people from the
Russian embassy were sent home for activities which are not in line
with the diplomatic service," Lithuania's Foreign Minister, Antanas Valionis, told a news conference.
"We regret that we were forced to take such an action."
He said the Russians had been expelled for "trying to illegally influence privatisation, and to illegally obtain information from the parliament related to the president's impeachment".
He did not elaborate and did not take questions.
Russian foreign ministry spokesman Alexander Yakovenko
told the Interfax news agency that Russia "considers such
a decision to be an unfriendly step by the Lithuanian side
in relation to Russia".
He said: "The Russian side retains for itself the right to
adequate steps in response."
Impeachment proceedings against President Paksas began
late last year, and a vote is expected in April.
Mr Paksas says he is innocent and has refused repeated calls for him
Lithuania and the two other Baltic states, Latvia and Estonia, are preparing
to join the European Union and the Nato military alliance later this year.