Israel responded with tank fire into Syria on Thursday after a Syrian mortar shell landed in the Israeli-occupied part of the Golan Heights, the army said.

"In response to the projectile that hit Israel earlier today, the Israel Defence Forces targeted the sources of fire in the Syrian Golan Heights," it said in an English-language statement.

It did not identify the sources of the Syrian fire nor say whether it considered it to be a deliberate attack or unintentional spillover from the Syrian civil war, as in several previous incidents.

It said the mortar shell fell on open ground and caused no injuries.

Speaking shortly afterwards in the Jordan Valley, part of the Israeli-occupied West Bank, Israeli Prime Minister Benjamin Netanyahu implied that the Syrian shell was a stray but said it was nevertheless unacceptable.

"We do not accept spillovers and if they hit us we return fire -- and it doesn't take much time," his office quoted him as saying in Hebrew.

On Monday, Israel carried out an air strike on an anti-aircraft battery in Syria after the battery fired on its planes during surveillance flights over neighbouring Lebanon.

Israel has sought to avoid becoming directly involved in the six-year civil war in Syria, though it acknowledges carrying out dozens of air strikes to stop what it calls advanced arms deliveries to Lebanese Shiite group Hezbollah.

The group, against which Israel fought a devastating 2006 war, is militarily backing Syrian President Bashar al-Assad's regime in the conflict.

Israel seized 1,200 square kilometres (460 square miles) of the Golan Heights from Syria in the Six-Day War of 1967 and later annexed it, a move never recognised by the international community.