At least 14 people were killed when multiple explosive devices struck a police truck transporting prisoners in a tense area of northwestern Syria on Saturday, the state-run news agency and an opposition group said.

Government troops also battled defectors in the north in fighting that left 10 people dead.

The state news agency SANA blamed the attack on "terrorists" and said it occurred on the Idlib-Ariha highway, an area near the Turkish border that has witnessed intense fighting with army defectors recently.

Four bombs that went off in "two phases" hit the truck, and then attackers targeted an ambulance that arrived to assist the wounded, SANA reported.

Six policemen who were accompanying the prisoners were also wounded, some of them in critical condition, it said.

The British-based opposition activist group, the Syrian Observatory for Human Rights, confirmed the incident Saturday and put the toll at 11 dead prisoners.

Rami Abdul-Rahman, director of the group, said the truck was hit by several roadside bombs, but it was not clear who was behind the attack.

There was no immediate claim of responsibility, but members of the so-called Free Syrian Army are known to be active in the area.

A Syria-based activist said the area has several army encampments and is full of roadside bombs planted to target army tanks passing by, adding that the truck carrying prisoners may not have been the intended target.

The activist spoke on condition of anonymity for fear of reprisals.

The 10-month uprising against Syrian President Bashar Assad has turned increasingly militarized and chaotic as more frustrated regime opponents and army defectors arm themselves and fight back against government forces.

The capital has seen three suicide bombings since late December which the government blamed on extremists.