Travellers in the Middle East have been urged to flee Syria as government forces move into the northern town of Jisr al-Shughour to crush dissent.
Heavy fighting was reported by state media, with armed groups using tanks and helicopters to attack anti-government protestors.
Reports suggest two people have been killed, while large numbers have also been arrested.
The government says it is trying to restore order after it claimed 120 security personnel had been killed.
British authorities have warned against all travel to the destination.
“We advise against all travel to the Syrian Arab Republic,” read a statement from the Foreign & Commonwealth Office.
“This is because of continued violent disturbances in urban centres across the country, including the capital Damascus, and reports of live gunfire by security forces resulting in a significant number of deaths.
“In light of the current security situation, British nationals in Syria who have no pressing need to remain should leave now by commercial means.”