Washington, Jun 13 (IANS/RIA Novosti): The US suspects Russia of supplying Syria with combat helicopters that will be used against peaceful protestors, US Secretary of State Hillary Clinton has said.

"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," she said, adding the US wants Russia to stop supplying Syria with all kinds of weapons.

"We have confronted the Russians about stopping their continued armed shipments to Syria," she said. "They have from time to time said that we shouldn't worry, everything they're shipping is unrelated to their actions internally. That's patently untrue."

President Vladmir Putin denied in early June that Russia was supplying arms to Syria which could be used against protestors.

Syria is one of Russia's major weapons clients, and Moscow has opposed a proposal for a UN arms embargo on Damascus.

According to UN estimates, about 10,000 people have been killed in Syria since the beginning of a popular uprising against President Bashar al-Assad in March 2011, which started with peaceful protests. It has, however, since turned increasingly militarised.