"Israeli warplanes launched over 100 strikes in Syria today, including on the Barzah scientific research centre," Rami Abdel Rahman who heads the Syrian Observatory for Human Rights told AFP.

He also reported "increased Israeli strikes to destroy the former regime's military capabilities".

Abdel Rahman said the targets of Israeli strikes included weapons depots in the eastern Deir Ezzor province and near the Qamishli military airport in the country's northeast.

Raids also destroyed boats from the former Syrian navy in the sea port of Latakia, he said.

Israel, which borders Syria, has sent troops into a buffer zone on the east of the Israeli-annexed Golan Heights after Assad's fall, in what Foreign Minister Gideon Saar described as a "limited and temporary step" for "security reasons".