A mortar shell fired from Syria exploded in the Israeli-occupied Golan Heights on Tuesday, hitting an open field without causing any casualties or damage, an army spokeswoman said. It was the third incident of fire from the civil war in neighbouring Syria straying across the ceasefire line in 24 hours and came as tensions soared after Israel carried out weekend air strikes near Damascus. On Monday, two rockets fired from Syrian territory also exploded in open fields on the Israeli side. The Golan has been tense since the beginning of the conflict in Syria more than two years ago. However, there have been only minor flare-ups in the region to date, as Syrian shells have crashed in the occupied Golan and Israel has fired at the source in retaliation. Israel, which is technically at war with Syria, seized 1,200 square kilometres (460 square miles) of the strategic plateau during the 1967 Six Day War, which it and later annexed in a move never recognised by the international community. The United Nations Disengagement Observer Force has been stationed in the Golan since 1974 to oversee a cease-fire.