BEIRUT — Lebanon's Hezbollah and the Syrian army made big advances against insurgents in the region north of Damascus on Wednesday, Hezbollah and Syrian state media said, shoring up President Bashar Al-Assad's grip on a crucial border zone. The gains in the mountainous Qalamoun region against groups including the Al-Qaeda-linked Nusra Front come at a time when Assad has suffered significant defeats elsewhere, notably in Syria's northwest. Hezbollah, an Iranian-backed Shiite group with a powerful militia, has been a crucial ally for Assad in the four-year-long war. Hezbollah fighters and the army seized Talat Moussa, the highest peak in the border area, the group's Al-Manar TV and sources briefed on the situation said, securing control of the area. Syrian state TV credited the advance to the army and “the Lebanese resistance”, an unusual public acknowledgement of Hezbollah's role in the battle for an area used by the insurgents to ferry supplies between Syria and Lebanon. The Syrian Observatory for Human Rights, a UK-based group that tracks the conflict, has reported that the intensity of Hezbollah's bombardment had forced many of the insurgents to withdraw. The offensive, in areas some 50 km (30 miles) north of Damascus, had been expected for some time but was awaiting the end of winter. It addresses one of the risks facing Assad, who has lost control of wide parts of the north and east in the conflict estimated by the United Nations to have killed 220,000 people. Since March, Assad has lost wide areas of Idlib province in the northwest at the border with Turkey, another supporter of the insurgency against him. He also lost the Nasib crossing with Jordan to rebels. Daesh, the single most powerful insurgent group in Syria, has also been launching attacks on both government- and rebel-held areas in central Syria, as it steps up efforts to expand beyond its strongholds. Daesh fighters killed around 30 government troops in an attack on Syrian army-held areas in Homs province overnight, the Observatory reported. At least 20 Daesh fighters were also killed in and around the town of Al-Sukhna, some 300 km (190 miles) northeast of Damascus. Security chief with Assad Syria's security services chief Ali Mamluk attended a meeting between Assad and an Iranian official, after a newspaper claimed he was under house arrest for plotting a coup. Mamluk's presence at the meeting, which was reported by the official news agency SANA, came after Britain's Telegraph newspaper said the top regime official had been sidelined. SANA said Mamluk was among the attendees at the meeting between Assad and the head of the Iranian parliament's national security and foreign policy committee, Alaedin Boroujerdi. — Agencies