Fighting raged Saturday between rebels and loyalist forces in Syria's northern Latakia province, a day after 34 people were killed as Islamists sought to seize a border crossing into Turkey, an NGO said.
The fighting has prompted President Bashar al-Assad's government to complain to the United Nations that Turkey was providing cover to rebels crossing the border from its territory.
Latakia province, which includes Assad's family village, is considered a regime stronghold, and many of its residents are from his Alawite minority.
Large parts of Latakia have remained relatively insulated from three years of fighting in Syria, but the province was shaken Friday as three Islamist groups battled to seize the Kasab border crossing.
The Syrian Observatory for Human Rights said the Islamists included the Al-Qaeda-affiliated Al-Nusra Front, who were also active in Saturday's clashes against regular troops and pro-regime militia.
At least 34 people were killed on Friday, including 13 rebels and five civilians, according to the Observatory.
Rami Abdel Rahman, director of the Britain-based Observatory, said fighting was under way in three government-controlled villages and another three that loyalists were trying to seize from rebels.
State news agency SANA said loyalists had "destroyed an ammunition and rocket depot, as well as vehicles transporting weapons... in numerous operations" in the north of the province.
And a security source said the army on Friday had retaken two police stations that had been captured by "rebels infiltrated from Turkey".
The source said Damascus had sent a message to UN Secretary General Ban Ki-moon accusing Ankara of "providing cover" for the rebels and demanded that the Security Council "denounce this terrorist attack on Syrian territory".
"Terrorist" is the common regime term for rebels.
Friday's clashes came after Al-Nusra, Sham al-Islam and Ansar al-Sham announced the beginning of the "Anfal" campaign in the Latakia area.
On another front, rebels on Saturday seized a strategic hill west of the city of Aleppo in northern Syria, the Observatory said.
It said 21 pro-government forces and 18 rebels were killed in the battle for Shwayhneh hill that raged for several hours.
More than 146,000 people have died in the three-year war, and millions more have been displaced.