Syrian government forces backed by helicopters clashed on Tuesday with rebels in several towns in the coastal province of Latakia, the Syrian Observatory for Human Rights said.
"The clashes started seven hours ago. These are the heaviest clashes so far in the area since the beginning of the revolution (in March 2011)," Rami Abdelrahman, the head of the British-based Observatory, told Reuters.
He said at least five tanks and armoured personnel carriers were destroyed. Rebels have taken over police stations in the city of Haffeh in the countryside of Latakia, he added. He said "a lot of ambulances" were seen arriving in the city of Latakia carrying government forces casualties.
"Haffeh is totally surrounded right now," said an activist in the city. He said the clashes were in the villages of Bekas, Babna, Jankeel.
Latakia has been relatively calm in the uprising against the rule of President Bashar al-Assad, who is from minority Alawite sect. Anti-government demonstrations have been in the Sunni neighbourhoods of Latakia, a majority Sunni area with a large Alawite population.
Syria imposes restrictions on foreign journalists making it difficult to verify events.