BEIRUT, July 14 (Reuters) - Seven fighters from the Lebanese group Hezbollah were killed in fighting with Sunni Islamist insurgents in a mountainous area on the Syria-Lebanon border in which at least 16 rebels were also killed, a monitoring group reported on Monday.
The Syrian Observatory for Human Rights, an opposition-affiliated watchdog, said a further 31 fighters from Hezbollah had been wounded in the fighting in the border area between Ras al-Maara in Syria and Arsal in northeast Lebanon.
There was no immediate comment from Hezbollah, an Iranian-backed Shi'ite Islamist group whose fighters have been aiding Syrian President Bashar al-Assad in the Syrian civil war.
A Lebanese security official and a source close to Hezbollah said at least two Hezbollah fighters and 27 rebels had been killed in the fighting that erupted on Sunday.
Syrian government forces backed by Hezbollah fighters have driven rebels from major towns along the border with Lebanon in the last year. That has helped to shore up Assad's control in a corridor of territory stretching north from Damascus and driven remaining rebels into the mountains at the border.
The Observatory said Hezbollah had captured 14 Islamist fighters from groups including the Nusra Front, al-Qaeda's official affiliate in the Syrian war.
Syrian government forces and Hezbollah "control the area, but they don't control every cave and mountain. There are many areas to hide in the mountains", said Rami Abdurrahman, the Britain-based head of the Observatory. (Writing by Tom Perry; Editing by Hugh Lawson)