Overnight clashes between security forces and army defectors in northern Syria left 12 soldiers and defectors and three civilians dead early on Saturday, activists said.
Fighting has become more intense as rebels increasingly often confront security forces loyal to President Bashar Assad who are trying to suppress the eight-month-old protest movement against his rule.
- UN: Syria now in state of civil war
- Russia opposes arms embargo on Syria
- 'Syria committed crimes against humanity'
The Syrian Observatory for Human Rights said fighting broke out around midnight in the northern city of Idlib, near the Turkish border.
"Seven were killed from the army and regime security forces, including an army officer," the group said. "Three civilians and five defectors were also killed."
Syria faces mounting international and regional isolation as organizations such as the Arab League and the European Union, and the United States, demand that Damascus stop the bloodshed and talk to its opponents, and impose increasingly tough sanctions when it does not do so.
Syrian authorities say they are fighting foreign-backed "terrorist groups" trying to spark civil war who have killed some 1,100 soldiers and police since March.
The head of the main group of army deserters who have joined the opposition, the Free Syrian Army, said that his forces were switching their tactics from seizing equipment and hitting security checkpoints to attacking the military directly.
He said this was a necessary response to an increasing use of violence in Damascus' military crackdown on protests.
Meanwhile, the Syrian government has reportedly banned the use of iPhones across the country in what seems to be an effort to prevent activists from documenting the ongoing uprising and government violence against protesters.
The Lebanese website el-Nashara said that the Syrian Finance Ministry issued an official statement saying that "the authorities warn anyone against using the iPhone in Syria."
According to the Russian news site Ria Novosi, protest groups in Syria are using a special iPhone app – "Syria Alone" – that offers independent news reports and "a collection of videos and jokes" that mock Assad.
Activists have warned that the order has "made it so that it is enough for any tourist or guest visiting Syria who owns an iPhone to be suspected of being a spy.
Reuters contributed to this report
- Receive Ynetnews updates
directly to your desktop