Syrian troops have fought intense battles on Saturday against rebels who are trying to capture two military bases in the north-west and step up their attacks on army compounds elsewhere in the nation, activists said.
The Britain-based Syrian Observatory for Human Rights and the Local Coordination Committees (LCC) said the rebels destroyed at least one tank near the town of Khan Sheikhoun in Idlib province.
The rebels, who have been battling for weeks to take control of bases in Wadi Deif and Hamdiyeh, are working to cut off supply routes to the compounds, the Observatory said. Attacks on government bases are a recent focus of fighting in Syria's conflict, which according to the UN has killed more than 60,000 people since March 2011.
Last week, rebels captured the nearby air base of Taftanaz, dealing a significant blow to president Bashar Assad's forces, which have relied on its airpower in its fight against the opposition.
The rebels also have been trying to capture other air bases in the northern province of Aleppo and, according to activists, were attacking the air base of Mannagh near the Turkish border.
In Turkey, state-run Anadolu news agency said Syria's air force targeted a mosque and a school building that apparently was sheltering displaced Syrians in the town of Salqin, some four miles from the border with Turkey in Idlib province. Dozens of people were killed and wounded. At least 30 people wounded in the attack were taken across the border to Turkey for treatment, and two died in Turkish hospitals, the news agency said.
The displaced Syrians were eating when the school was attacked, according to Anadolu, who interviewed witnesses who crossed into the Turkish border province of Hatay. The wounded included women and children, the agency said.
Rami Abdul-Rahman, who heads the Observatory, said the government was sending reinforcements to the central city of Homs where rebels have controlled some neighbourhoods for more than a year. Residents of Homs, Syria's third largest city, were one of the first to rise up against Assad and many refer to it as "the capital of the revolution". "It seems they are preparing for a big attack on Homs," Abdul-Rahman said by telephone.
The Observatory and the LCC said troops attacked several suburbs of the capital, Damascus, as well as Homs and the southern rebel-held town of Busra al-Harir. The shelling and air raids targeted the Damascus suburbs of Douma, Daraya and Moadamiyeh where regime forces have been on the offensive for weeks, they said.
Syrian state-run TV said government forces attacked a group of rebels as they met in the town of Boukamal near the Iraqi border, killing some of them.