The Russian government is not sending new helicopters to Syria, but it refurbishes copters it previously sold, a Russian official told CNN late Wednesday.

U.S. Secretary of State Hillary Clinton said this week the United States had information that Russian helicopters were being shipped to Syria, where a fierce crackdown against a grass-roots anti-government movement has persisted for 15 months.

Clinton stood by her comments even as Russian Foreign Minister Sergey Lavrov denied his country was sending any equipment that could be used against protesters.

"We are completing right now the implementation of contracts that were signed and paid for a long time ago," Lavrov said Wednesday after talks with his counterpart in Iran. "All these contracts concern exclusively anti-aircraft defense."

"Russia hasn't had a new contract in 20 years," the Russian official insisted to CNN on Thursday, providing further details about Russia's dealings with Syria.

The Russian official, who asked not to be named because of the diplomatic sensitivity of the issue, could not speak specifically about the helicopters Clinton mentioned.

The distinction between modern or overhauled helicopters is not relevant for the U.S. government.

"New or refurbished, they kill just as well," a senior administration official said Thursday.

Another U.S. official said the belief is that the equipment is fulfilling an existing contract and is on a ship en route to Syria. The official would not provide specifics on whether this was spare parts or fully assembled helicopters, though the official added that the U.S. knows "what type of helo" is being sent.