Syrian troops and rebels clash near 2 besieged bases in northeast

This photo released by the Syrian official news agency SANA, shows damage after a rocket slammed into a building, killing at least 12 people, in Aleppo, Syria, Friday, Jan. 18, 2013. In a spike in civil war violence that Syrian state media blamed on rebel fighters a rocket attack in the northern city of Aleppo occurred during a particularly bloody week nearly two years after an uprising began against Assad's regime. (AP Photo/SANA) (The Associated Press)

This photo released by the Syrian official news agency, SANA, shows rescue workers and bystanders at a building damaged by a rocket attack, that killed at least 12 people, in Aleppo, Syria, Friday, Jan. 18, 2013. In a spike in civil war violence that Syrian state media blamed on rebel fighters a rocket attack in the northern city of Aleppo occurred during a particularly bloody week nearly two years after an uprising began against Assad's regime. (AP Photo/SANA) (The Associated Press)

Syrian activists report intense fighting between government troops and rebels trying to tighten their siege of two military bases in the northeast.

The Britain-based Syrian Observatory for Human Rights and the Local Coordination Committees say rebels destroyed at least one tank near the town of Khan Sheikhoun in Idlib province on Saturday.

Rebels have been attacking the nearby bases of Wadi Deif and Hamdiyeh for weeks. The Observatory said the rebels are trying to cut roads that supply the two bases.

Besieged government bases are a recent focus of fighting in Syria's conflict, which according to the U.N. has killed more than 60,000 people since March 2011.

Last week rebels captured the nearby airbase of Taftanaz, dealing a significant blow to President Bashar Assad's regime.