Israelinfo-icon launched repeated rounds of rocket fire into Syriainfo-icon early on Thursday, Syrian state mediainfo-icon reported, after Israel's military said Iranian forces in Syria had fired missiles at Israeli armyinfo-icon positions in the occupied Golan Heights.

"The Syrian air defences are confronting a new wave of Israeli aggression rockets and downing them one after the other," state news agency SANA reported.

Israeli warinfo-icon planes were shooting the rockets from inside the Occupied Palestinian territories and targeting the City of Baath in Quneitra province, that was shelled shortly after midnight, the state news agency said.

State-run al-Ikhbariya TVinfo-icon broadcasted live feed of the air defences as they were confronting the Israeli rockets.

The scale of Israeli rocket fire appeared to be far higher than in previous incidents.

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Syrian activists reported Israeli airstrikes hitting targets near Damascus. One video posted online showed a large explosion and shrapnel flying in the air. Residents reported loud sounds that rocked their buildings. It was not immediately clear what was hit.

An Israeli army spokesman, Avichay Adraee, said on Twitterinfo-icon that Israel was "acting against Iranian targets inside Syria," a rare admission by an Israeli official.

Syrian media earlier said the hostilities began with Israeli fire at Syrian positions in southern Syria from across the border.

Pro-Syrian media said Syrian missiles then fired at Israeli forces. One TV station, Beirut-based Al-Mayadeen, said at least 50 missiles were fired from Syria at Israeli forces in the Golan Heights. Al-Ikhbariya TV said missiles targeted 10 Israeli positions.

Syrian media said it was the first time in years that Syrians had fired at Israeli forces in the occupied Golan Heights.

Earlier, the Israeli army said the Iranian al-Qods brigade in Syria had fired around 20 rockets and missiles at Israeli army positions in the occupied Golan Heights.

Israel "views this Iranian attack very severely," army spokesman lieutenant-colonel Jonathan Conricus told reporters. He said Israel had responded, but did not provide details.

"This event is not over," he said.

Expectations of a regional flare-up were stoked by USinfo-icon President Donald Trumpinfo-icon's announcement on Tuesday that he was withdrawing from the Iranian nuclear deal.

Hours later, an Israeli airstrike in Syria killed 15 people, including eight Iranians, the Syrian Observatory for Human Rightsinfo-icon said.

Israel has neither confirmed nor denied responsibility.