Jihadists from the Islamic State group took control of the northern sector of Syria’s historic city of Palmyra on Wednesday, a monitor said.

“IS fighters seized the northern parts of the city, which amount to a third of Palmyra,” said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights.

“Regime forces fled from these neighbourhoods,” he added.

Palmyra’s UNESCO world heritage site ruins, including ancient temples and colonnaded streets, are in the city’s southwest.

State television said “armed forces targeted IS terrorist groups north of Palmyra, and blocked their infiltration of the northern parts of the city”.

It was the second time IS has overrun northern Palmyra, after it seized the same neighbourhoods on Saturday but held them for less than 24 hours.

The jihadists were locked in fierce clashes with regime forces on the city’s northern edges, as well as in the east near the notorious Palmyra prison.

They managed to seize a government state security building and spread out through northern districts, the Observatory reported.

Mohammad, an activist originally from Palmyra, told AFP that “regime soldiers fled after IS took the state security building” in the north of the city.

“They headed to the military intelligence headquarters near the ruins,” he added.