Russia, defying pressure from the U.S. Senate, talked tough to the Baltic States on Thursday, warning that a planned visit to Latvia by Prime Minister Viktor Chernomyrdin may be put off and that a pullout of troops from Estonia would not take place on schedule.


Vyacheslav Bakhmin, a senior Russian Foreign Ministry official in charge of human rights told a briefing that Latvia's proposed new citizenship law, which threatens to disenfranchise most of the Russian-speaking population, might torpedo the trip by Chernomyrdin, planned for the near future.


"Everything depends on the climate of relations, and the visit was fixed during a breakthrough in our relations when it seemed serious obstacles to our cooperation had been removed," Bakhmin said.


"It may have to be postponed," he added.


Moscow and Riga agreed in May that Chernomyrdin would visit Latvia to boost economic contacts between the two nations after signing a package of agreements on the pullout of the last remaining 10,000 Russian troops from the Baltic republic by August 31.


In a separate development, Latvian Prime Minister Valdis Birkavs, whose cabinet signed the deal with Russia, announced the resignation of himself and his government on Thursday, following the collapse of the ruling coalition.


Ivars Embrekts, head of the Latvian Foreign Ministry's press center in Riga, said by telephone that as far as he was aware, Chernomyrdin's visit would still go ahead in the near future.


Embrekts said that the citizenship law was a "Latvian internal matter" and should not affect Riga's relations with Moscow.


Bakhmin said Thursday that the agreements on troop pullout "have been signed and we do not intend to reconsider them."


The Baltic states have been the subject of a sparring match between Moscow and Washington over the last two weeks after President Bill Clinton made a historic trip to Riga and gave an emotional endorsement to the new nation's drive for self-determination.


But at last week's summit of G-7 nations in Naples, President Boris Yeltsin contradicted Clinton and said that Russia would not meet the August 31 deadline for the pullout of troops from Estonia.


The U.S. Senate responded Wednesday by voting to require all Russian troops to be pulled out of Latvia and Estonia by August 31 before Russia can get American aid.


The 89-8 vote came on an amendment to a foreign aid bill which provides $839 million in U.S. aid to Russia and the other former Soviet republics. The original draft had given Russian troops until December 31 to leave the Baltic nations. There are only a little over 2,000 Russian troops left in Estonia but negotiations on their withdrawal have been deadlocked despite a provisional plan to pull them out by August 31.


Bakhmin said that Estonia's treatment of its Russian minority now put that plan in jeopardy. "It hardly makes sense to talk about August 31 as the date of withdrawal of troops from Estonia because the Estonian side took what is from our point of view a completely unconstructive position," he said.


Yeltsin told Clinton in Naples that he was willing to meet Estonian President Lennart Meri to try to resolve the troops issue. The offer was welcomed by Estonian leaders Thursday.


But a joint statement issued by Meri, Prime Minister Mart Laar and parliamentary speaker Ulo Nigis also criticized Yeltsin for failing to keep to the August 31 deadline. AP quoted the statement as saying that Yeltsin's "failure to fulfill the commitments made by Russia and comply with the norms of international law is deeply disappointing."


Bakhmin said the date of withdrawal was not the key issue, and that no one should doubt Moscow's commitment to pull the troops out. The withdrawal agreements still need to be ratified by the State Duma, which was debating the issue Thursday.


The Russian authorities and opposition have made common cause of the emotive issue of Estonia and Latvia's apparent intolerance towards their Russian-speaking populations.


Latvia's new citizenship law, which is expected to go before parliament for a final reading in the next two weeks, is set to introduce a quota system for residents who were not born in Latvia or did not have citizenship in pre-war independent Latvia. This takes in almost all of the Russians in the country.