VILNIUS (Reuters) -- Lithuanian Prime Minister Gediminas Kirkilas said that he hoped the expulsion of a Russian diplomat last week would not affect the Baltic state's relations with Moscow.

"I believe the diplomat was asked to leave on Friday," Kirkilas told Reuters in a telephone interview. "I hope the Russians understand that this step is not intended to worsen relations," he added.

He declined to name the diplomat or give a reason for the expulsion.

But Lithuanian President Valdas Adamkus said on Monday night that a Russian diplomat had been expelled for spying -- and he expected Russia to react by expelling a Lithuanian diplomat from Moscow. "The spy has been caught," he said in an interview on LNK commercial television. "Don't be surprised if Russia retaliates with the same measure."

The independent Baltic News Service (BNS), when reporting the expulsion on Sunday, quoted unnamed sources as saying the diplomat was a high-ranking Russian suspected of spying and of "seeking to influence Lithuania's determination to support Georgia in its conflict with Moscow".

A diplomatic crisis between Georgia and Russia erupted last month after Georgian authorities detained several Russian officers on suspicion of spying for Moscow. The officers were later handed over to the Organisation for Security and Cooperation in Europe.

Kirkilas said on Monday the expulsion was not related to Lithuania's stand on the Georgian-Russian crisis. "I do not think it has anything to do with Georgia," he said.

The affair comes at a sensitive time in relations between Lithuania and its giant neighbor. Western diplomats in Vilnius said they were not surprised by the expulsion. "Relations are tense enough as it is," said one western diplomat. "Lithuania felt it had to take a tough stand."

"We know the Russians are quite active in this area. The Lithuanians had to expel some people a couple of years ago," said another diplomat.

In 2004, Lithuania ordered out the Russian military attaché and two other diplomats for alleged intelligence activities. Moscow retaliated by expelling the Lithuanian military attaché.

Lithuania's road to independence from Moscow in 1991 was more troubled than that of other Soviet republics.

An independence bid the previous year was throttled by a Soviet economic blockade and in early 1991, 13 unarmed Lithuanian civilians were killed defending the Vilnius TV tower from an attack by an armored KGB unit.