Syria's state news agency SANA said its air defence systems downed several missiles launched from Israeli warplanes.

The Observatory said missiles struck Wadi al-Oyoun in the central province of Hama, near a scientific research centre which was already targeted by Israeli strikes in July and last year.

Iranian military positions in the coastal region of Banias, in the province of Tartus, were also targeted, the Britain-based Syrian Observatory for Human Rights monitoring group said.

Three Syrian soldiers were killed and 23 people injured -- 14 Syrian and nine Iranians, according to the Observatory.

"The air defence system responded to an Israeli aggression carried out by aircraft... that targeted some of our military positions in the provinces of Tartus and Hama," SANA said, quoting a military source.

"Some of the missiles" were downed, the agency said, reporting an initial casualty toll of one dead and four wounded.

A spokesman for the Israeli army refused to comment on the new raids, but an Israeli military official, in a rare confirmation, said the army had carried out some 200 strikes in Syria over the past 18 months against mainly Iranian targets.

Israel has pledged to prevent its main enemy Iran from entrenching itself militarily in Syria, where Tehran is backing President Bashar al-Assad in the ongoing civil war.

A series of strikes that have killed Iranians in Syria have been attributed to Israel in recent months, but the Israeli military rarely confirms them.