Sectarian violence has erupted again in Syria, raising fresh doubt on the ability of the new Islamist rulers to control armed factions and calm tensions.

Israel said it carried out a strike in Syria against "an extremist group" that attacked members of the Druze community, following through on a promise to defend the minority group as deadly sectarian violence spread near Damascus on Wednesday.

The strikes were south of Damascus, where Syrian security forces say they are battling gunmen from the religious minority.