Russia's foreign minister discussed Syria peace plan with US Kerry

It also said that Lavrov informed Kerry that a U.S. decision to ease some restrictions on arming Syrian rebels may lead to more casualties.

Syria has been suffering from an armed conflict since March 2011, which, according to the UN, has so far claimed over 500,000 lives.

Militants from various armed groups are confronting the Syrian government troops.

The IS, YPG and PYD are the most active terrorist groups in Syria.