MOSCOW (AP) — Russia is calling for an independent probe by UN experts into what Syrian rebels allege was a chemical weapons attack this week by government forces on the outskirts of Damascus.

The Russian Foreign Ministry says Minister Sergey Lavrov discussed the situation by telephone Thursday with Secretary of State John Kerry and they concluded they have a "mutual interest" in calling for the investigation.

President Barack Obama tells CNN the possible attack is "a big event of grave concern."