WASHINGTON -- Cuba has tentatively accepted two U.S. requests to enhance antinarcotics cooperation between the countries, even as leading Republican lawmakers portray the nation as a major trafficker, U.S. and Cuban sources said.

Cuban officials have told U.S. diplomats they are willing to let the Clinton administration station an anti-narcotics agent at the U.S. mission in Havana, and would be prepared to collaborate on a continuing basis. If final details are worked out, the agent would probably be a Coast Guard officer equipped with electronic devices to detect drugs in containers.

Cuba has also agreed to upgrade its communication links with Coast Guard officials, allowing for voice contacts between enforcement authorities and a secure radio link, the sources said. Currently, Coast Guard officials contact their counterparts by fax on a case-by-case basis and use radio frequencies that can easily be monitored by traffickers.

The government of President Fidel Castro has proposed, moreover, that both countries meet on a regular basis to discuss antinarcotics operations. But administration officials are cool to that idea, saying Havana is seeking to build its political legitimacy through routine contacts.

Administration officials on Wednesday sought to downplay Cuba's agreement just seven weeks after they traveled to Havana to ask for the changes. Republican lawmakers harshly criticized the visit and have called on the President to halt intelligence sharing with Cuba and subject the island to penalties as a major trafficking nation.

An administration official who is monitoring the contacts with Cuba minimized the progress Wednesday as part of an ongoing effort.

``This is not revolutionary and new,'' he said, after asking not to be named. Antidrug cooperation with Cuba, he said, ``is something that has had concrete success in the past. This is a way to systematize it in the future.''

But on Capitol Hill, some Republican lawmakers were swift to condemn any effort to upgrade relations. The Cubans are seizing on U.S. concerns over drugs to try to open a broader political dialogue, said Marc Thiessen, spokesman for Sen. Jesse Helms, chairman of the Foreign Relations Committee.

``They see it as a path toward normal relations with the United States and a chance to whitewash their drug record,'' Thiessen said.

Drug-smuggling is the most prominent of several national security concerns involving Cuba that have recently pitted the Clinton administration against hard-line anti-Castro lawmakers. In recent years, Castro foes have denounced Cuba's intermittent construction of a Soviet-style nuclear power plant, the potential for mischief by its biotech industry and the Soviet eavesdropping post at Lourdes.

The administration has long maintained that it benefits from antinarcotics cooperation with Havana. Drug czar Barry McCaffrey recently said there is ``no conclusive evidence to indicate that the Cuban leadership is currently involved in this criminal activity.'' U.S. officials praise Cuban cooperation for netting nearly eight tons of cocaine aboard a Honduran freighter in 1996.