A string of explosions rocked fuel and weapons stores at an airbase in Syria's central Hama province on Friday, killing at least 11 pro-government fighters, the Syrian Observatory for Human Rights.

The UK-based war monitor said the blasts were likely due to a "technical problem".

"The explosions struck several regime depots of weapons and fuel at Hama military airport," Observatory chief Rami Abdel Rahman.

Eleven government troops were killed, including members of allied militias, and dozens more wounded or still unaccounted for, Abdel Rahman said.

Images and videos posted on social media showed enormous plumes of smoke rising from the facility, with explosions reportedly felt in nearby Hama city.

The blasts were reported to have occured both inside and outside the airbase.

Syria's official media also reported the explosions at the base, which lies to the west of Hama city and from which the Syrian government's air force conducts bombing raids elsewhere in the province and on the northern rebel stronghold of Idlib.

The official Syrian news agency, SANA, reported that "explosions were heard in the vicinity of Hama airport", but did not elaborate.

Tensions are high in Syria after several Israeli bombing raids in recent weeks on government positions, as well as on military instillations reportedly used by Iran.

The latest wave came in the early hours of 10 May, when Israel carried out dozens of raids against what it said were "Iranian" targets in Syria.

It has repeatedly threatened to act if Iran developed an entrenched military presence in southern Syria, which borders the Israeli-occupied Golan Heights.