BEIRUT, March 21 (Reuters) - Syrian rebels have overrun several towns near the Israeli-occupied Golan Heights in the past 24 hours, rebels and a monitoring group said on Thursday, fuelling tensions in the sensitive military zone.
"We have been attacking government positions as the army has been shelling civilians, and plan to take more towns," said Abu Essam Taseel, from the media office of the "Martyrs of Yarmouk", a rebel brigade operating in the area.
The Syrian Observatory for Human Rights, a British-based group monitoring the conflict in Syria, said rebels had taken several towns near the Golan plateau, which Israel captured from Syria in the 1967 Middle East war and later annexed.
It said that on Wednesday night rebels had captured Khan Arnabeh, which sits on the Israeli-Syrian disengagement line and straddles a main road leading into Israeli-held territory.
Rebels also took Mashati al-Khadar and Seritan Lahawan, two villages near the ceasefire line, it said.
U.N. peacekeepers monitoring the line halted patrols this month after rebels held 21 Filipino observers for three days.
The armed struggle between rebels and forces loyal to Syrian President Bashar al-Assad has posed increasing difficulties for the 1,000-strong U.N. Disengagement Observer Force (UNDOF).
There is growing concern in Israel that Islamist rebels may be emboldened to end the quiet maintained by Assad and his father before him on the Golan front since 1974.
Rebel sources say the Syrian army intensified shelling of villages in the area of Saham al-Golan at dawn on Thursday.
They said that rebels in the Quneitra region, next to the Golan, were stepping up attacks on roadblocks to gain more territory but added that the strategic town of Quneitra - which was largely destroyed and abandoned during Israeli-Syrian clashes in 1974 - was still in Syrian government hands. (Reporting by Oliver Holmes in Beirut and Suleiman al-Khalidi in Amman; Editing by Alistair Lyon)