GOLAN HEIGHTS/AMMAN - Pro-Assad forces raised the Syrian flag in the largely ruined city of Quneitra on Thursday, regained from surrendering rebels as the government tightens its hold on the Syrian sector of the Golan Heights, strategic territory bordering Israel and Jordan.A Reuters photographer saw uniformed men raise the Syrian national flag and the black, white, green and red flag of President Bashar Assad's Baath Party in the long-abandoned city. No weapons were immediately visible. The photographer was reporting from a vantage point on the Israeli western section of the Golan Heights.Forces supporting Assad, backed by a major Russian air campaign, have been pushing into Quneitra province after an offensive last month that routed rebels in adjoining Deraa province who were once backed by Washington, Jordan and Gulf states.Pro-Assad forces began pushing last week towards the border area close to the demilitarized zone adjoining the Israeli territory after rebels surrendered large parts of Quneitra province.The Russians reached a deal with the last group of mainstream rebels in control of the rebel part of northwestern Quneitra province in a deal that now effectively brings the whole of the border frontier under state control, an opposition source said.Under the terms of a 1974 U.N. armistice that demilitarized much of the Golan, Israel withdrew from the abandoned capital of Quneitra province which it had razed to the ground after capturing it in the 1967 Arab-Israeli war. The destroyed town had fallen into rebel hands in 2014.Pro-Assad forces have raised the flag in several other towns along the frontier, including al Hamidiyah and Rafid, that overlooks a U.N. observation post.A Russian-brokered deal allows the return of Syrian army brigades that existed before the conflict began in 2011 to where they were stationed near the demilitarized zone.So far there have been no signs of a significant deployment of Syrian army troops to former posts near the frontier, according to a regional intelligence source.Israel says it is concerned that Assad may defy the U.N. armistice, or let his Iranian and Lebanese Hezbollah reinforcements deploy there.There is a strong presence in parts of Quneitra of Iranian-backed militias, the intelligence source said, adding that they have taken a low profile to avoid antagonizing Russia which had given pledges to Israel to curb their influence.The Israeli government has signaled it would not impede the Syrian army presence in Quneitra as long as it kept away from the demilitarized zone. However, Israel said it will continue to escalate attacks along its frontier and elsewhere in Syria where it suspects Iranian-backed forces are stationed.Mainstream rebels are completing a handover of weapons and in some instances negotiating with Russian officers about enlisting in army units that serve as local forces, opposition sources say.Several hundred mainly jihadist rebels from a former al Qaeda offshoot have rejected the deals and accepted safe passage to opposition-held parts of northern Syria.Rebels say army and pro-government militias have been putting up checkpoints in former rebel held-towns in Quneitra province that have accepted the return of state ruleThe army is still battling a local Islamic State affiliate around the Yarmouk Basin nearby, where the army said on Thursday its ground forces had made significant progress after nearly 10 days of relentless Russian-led bombing.An army source was quoted on state media as saying the towns of Tseel and Adwan had now been seized alongside the commanding heights of Tel Jamou, which the militants had been fiercely defending.