Russia's arms export agency said Wednesday its deliveries to Syria were in line with UN regulations but declined to comment specifically on US claims that it was sending attack helicopters to the regime.

Rosoboronexport "does not supply weapons and military technology in contradiction with UN Security Council security requirements and other international agreements," an agency spokesman told the state-run RIA Novosti news agency. `

The news report said the spokesman "did not comment" when asked about the specific charges.

US Secretary of State Hillary Clinton on Tuesday accused Russia of recently sending the shipment to its Soviet-era ally.

"We are concerned about the latest information we have that there are attack helicopters on the way from Russia to Syria, which will escalate the conflict quite dramatically," Clinton told a think-tank discussion in Washington.

Russia has always argued that it was only supplying Syria with weapons such as air defence systems that could not be used against civilians in the army's standoff with the armed opposition.

A Russian foreign ministry spokesman contacted by AFP said Moscow may issue a comment on Clinton's charges later in the day.