Moscow, Dec 28 (IANS): Russian Foreign Minister Sergey Lavrov voiced his concerns over possible US arms deliveries to Syrian rebels in a phone conversation with US Secretary of State John Kerry, Russian Foreign Ministry said.

Lavrov told his US counterpart on Tuesday that the US decision to ease some restrictions on arming Syrian rebels may further escalate tensions and lead to more causalities in the war-torn country, Xinhua news agency cited a statement by the ministry.

Last week, the outgoing US President Barack Obama signed an annual defence spending bill into law, which allows providing "man-portable air defence systems to the vetted Syrian opposition."

Earlier this December, Obama lifted restrictions on military aid to foreign forces in Syria in the Arms Export Control Act.

Lavrov said the moves by the Obama administration were aimed at undermining the foundation for the normalization of Moscow's ties with the upcoming US administration under Donald Trump.