According to the activists based in Syria, at least a dozen Syrian secret police have defected from an intelligence compound, in what appeared to be the first major desertion from a service that has acted as a pillar of President Bashar al-Assad's rule.

A gunfight broke out overnight on Saturday after the defectors fled the Airforce Intelligence complex in the centre of Idlib city, 280 km (175 miles) northwest of Damascus.

They estimate the number of defectors from the military so far at several thousand, mainly army recruits from Syria's Sunni Muslim majority. Members of Assad's minority Alawite sect, an offshoot of Shi'ite Islam, have a tight grip on the country's military and security apparatus.

Opposition sources said another 16 soldiers defected from Idlib on Sunday and fighting separately broke out between a new group of defectors, of similar size, and loyalist forces to the south, in the Josieh area on the border with Lebanon.

The activists reported on Sunday that ten people on both sides were killed or wounded during the fight.

The defections came as the Arab League once again chided Syria for failing to sign up to a league-backed plan to end the violence in Syrian cities.

The diplomat said that, “We are very clear after the meeting yesterday. We give the Syrians one day, and I hope we will receive the answer from them. But until now I think there has been no answer from Syria”.

The Arab League had told Syrian authorities to sign an initiative to end the military crackdown on popular protests by Sunday, threatening to impose financial and economic sanctions if it does not sign soon.

A senior Arab diplomat at the League said late on Sunday that there was no sign Syria had responded to the deadline.

The top U.N. human rights forum has condemned Syria for “gross and systematic” violations by its forces, including executions and the imprisonment of some 14,000 people.

Protests, modeled on “Arab Spring” revolts that have toppled leaders in Tunisia, Egypt and Libya, have continued in Homs and scores of cities and towns.