Violence erupted in two Syrian provinces on Tuesday, with a rights group reporting 10 civilians dead in an army mortar attack and 12 soldiers killed in a fire-fight with rebel gunmen as U.N. monitors sought to shore up a shaky ceasefire.    

The Britain-based Syrian Observatory for Human Rights, which tracks the 13-month-old uprising against President Bashar al-Assad, said nine members of one family died in mortar bomb blasts in a village in the northern province of Idlib.    

An activist on the Turkish border, Tareq Abdelhaq, said 35 people had been wounded and that some were being carried 25 km (15 miles) along mountain tracks to receive emergency treatment in refugee camps dotted along the frontier.    

"Some are being smuggled over the border to Turkey. They had to carry the wounded and go through the mountains to avoid checkpoints on the road," Abdelhaq said. "One guy died on the way. He was 19 years old and had very bad injuries."    

In the eastern Deir al-Zor province, troops hit back with mortar and heavy machinegun fire after losing a dozen of their own to insurgents, killing at least one villager and destroying a school, the anti-Assad Observatory added.    

The United Nations says Syrian forces have killed more than 9,000 people since the uprising began in March 2011.    

Its special envoy for children in war zones said more than 34 children were believed to have been killed since the U.N.-backed ceasefire nominally came into force on April 12.  

U.N. peacekeeping chief Herve Ladsous said on Tuesday that the United Nations is accelerating deployment of unarmed observers to Syria to ensure all 300 are on the ground by the end of May to monitor a shaky ceasefire.    

"We have 24 observers on the ground and I fully expect this number to increase rapidly over the next two weeks so that UNSMIS (U.N. Supervision Mission in Syria) will build up to full operational strength by the end of May," Ladsous told reporters.   

He said that observers had reported violations of the truce, implemented on April 12, by both Syrian President Bashar al-Assad's security forces and opposition groups.
  
Reuters