The Syrian army has lost control of two strategic bases in the northwestern province of Idlib to al-Qaeda-linked al-Nusra Front and other rebel factions following heavy fighting, a monitoring group said.

Al-Nusra Front, in coordination with rebel groups of Jund al-Aqsa and Ahrar al-Sham, seized Hamidiyeh and Wadi al-Deif army bases on Monday, according to the Britain-based Syrian Observatory for Human Rights.

Al-Nusra initially reported a victory in Wadi al-Deif, putting large areas of Idlib province, which borders Turkey, under their control. The Observatory said at least 31 government soldiers and 12 rebel fighters had been killed in the clashes that began on Sunday.

In its attack on Wadi al-Deif, "Al-Nusra Front used tanks and other heavy weapons that it captured last month from the (Western-backed) Syrian Revolutionary Front", said Observatory director Rami Abdel Rahman.

Within hours of their Wadi al-Deif takeover, the rebel groups also took over Hamidiyeh. "They took 15 soldiers prisoner from Hamidiyeh," said Abdel Rahman.

The capture of army bases in Idlib is being considered a blow to the Syrian government that had managed to hold the posts for more than two years and repelled repeated attacks by opposition fighters.

Rebels and the al-Nusra Front control much of the countryside of Idlib province while government forces dominated the provincial capital city, also called Idlib.

Al Jazeera