A leading Egyptian al Qaeda figure who joined its Syrian offshoot the Nusra Front and became a prominent figure in the militant group was killed in a drone attack in rebel-held Idlib province, two jihadist sources said on Monday.
Syrian rebels and a monitoring group said two explosions that struck a Syrian town near the Israeli-occupied Golan Heights were caused by an Israeli air strike but Lebanon's Hezbollah blamed rocket fire by al Qaeda-linked militants.
The Russian air force and Syrian military are preparing a joint operation to take Aleppo from rebels, the Syrian prime minister was quoted saying on Sunday, and an opposition official said a ceasefire was on the verge of collapse.
The Syrian army and its allies launched a major attack on insurgents south of Aleppo, described as the fiercest government assault in the area since an agreement to ease the fighting came into effect in February.
Heavy air strikes were reported to have hit rebel-held areas near Damascus as fighting raged across much of western Syria on Friday, hours before a plan aimed at halting the fighting was due to take effect.