Since the start of the Syrian war in 2011, Israel has carried out hundreds of strikes in the country, targeting government troops as well as allied Iranian forces and Hezbollah fighters, enemies of the Jewish state.

"From the occupied Golan airspace, enemy Israeli helicopters attacked positions in the southern region with several missiles," Syria's official SANA news agency said shortly after midnight.

The report said there was "only material damage" and did not specify the nature of the targets.

The Syrian Observatory for Human Rights, a Britain-based monitor, confirmed the strikes, saying they targeted military positions of the Iranian forces and pro-Iran militias.

The strikes come after three civilians were killed when "missiles fell on houses" near the Syrian capital Damascus just before dawn on Monday, SANA said, blaming Israel.

The Observatory reported four deaths in that attack, and said the strikes were on Iranian and Hezbollah forces.

Israel rarely confirms its operations in Syria but says Iran's presence in support of President Bashar al-Assad is a threat and that it will continue its strikes.

On April 20, SANA said Syrian air defences downed Israeli missiles near the ancient city of Palmyra.

The Observatory, which relies on a network of sources inside Syria, said three Syrian fighters and six foreigners were killed in strikes targeting "military posts for Iranian militias in the Palmyra desert".

The Syrian conflict has killed more than 380,000 people since 2011 and forced more than half of the country's pre-war population from their homes.