Associated Press

BEIRUT — Syrian government forces and their allies on Saturday said they seized the town of Mayadeen, an Islamic State stronghold in the country’s east, in a major gain in the race for territories previously held by the militant group.

The announcement came as U.S.-backed Syrian Democratic Forces said they were in the “final” battle for control of Raqqa, the ISIS' de facto capital and the symbol of the group’s reign of terror. However, officials with the Kurdish-led SDF said it could be hours or days before ISIS is uprooted from the city, to the north of Mayadeen.

Over the past months, Mayadeen had become a refugee for the IS leadership from Syria and Iraq as its self-proclaimed caliphate crumbled.

The town, on the western bank of the Euphrates River, was also a major node in the race for control of the oil-rich eastern Deir el-Zour province that straddles the border with Iraq.

SDF has steadily been making a bid for areas in the province, securing territory to the east of the river as the U.S.-backed offensive focused on the Iraq border area, still controlled by ISIS.

Washington fears further advances by Syrian government forces could help Iran, which backs militias fighting alongside the Syrian military, expand its influence across the region by securing a land route extending from from Iraq, Syria and Lebanon, all the way to Israel.

As the Syrian government launched its Deir el-Zour offensive in September, the U.S.-backed forces diverted some fighters from Raqqa toward Deir el-Zour to secure the Iraqi border. This prompted the government troops and allied militiamen to push south to Mayadeen, finally securing the town on Saturday.

The fall of Mayadeen would strangle ISIS militants in the city of Deir el-Zour, cutting their supply route from the south and the desert.

The pro-government Al-Ikhbariya TV quoted an unnamed Syrian military official as saying that ISIS’ defenses in Mayadeen collapsed on Saturday, with troops chasing last ISIS fighters out of town as corps of engineers cleared land mines.

Rami Abdurrahman, the head of the Syrian Observatory for Human Rights said government troops, backed by Shiite militias, have control of the town but are still combing it for militants.

With ISIS under fire in Deir el-Zour and Raqqa, the only remaining urban stronghold still in the militants’ hand is Boukamal, a strategic border town that had linked ISIS territory in Syria and Iraq.

Meanwhile, the US-backed Kurdish-led Syrian Democratic Forces, said the ISIS militants were putting up a desperate fight in its few remaining neighborhoods in Raqqa, spokesman Mustafa Bali, said. The U.S. coalition said about 85% of Raqqa was now controlled by the SDF.

Scores of civilians were seen in a video that surfaced Friday leaving Raqqa in desperate and terrified condition. They emerged from destroyed districts, some of them collapsing on the ground in exhaustion as they arrive to a Kurdish-held area of the city, in haunting scenes reflecting their years-old ordeal. Earlier this week, U.S. officials said an estimated 4,000 civilians are believed still trapped in the city.

Omar Alloush, a local Raqqa official, told The Associated Press on Friday that about 100 ISIS militants surrendered at once.

The Observatory said negotiations over the fate of foreign fighters who remain in Raqqa have delayed the final push to regain control of the city. But SDF officials deny there are talks to evacuate ISIS fighters. U.S. officials have said that only surrender, not a negotiated withdrawal for ISIS fighters in Raqqa, would be accepted while the top U.S. envoy for the anti-IS coalition Brett McGurk had said earlier foreign fighters in Raqqa will die in the city.

Losing Raqqa, in many ways the symbol of ISIS’ caliphate, would be yet another blow to the militant group and its reign of terror in the region as its strongholds crumble one after another in Iraq and other parts of Syria.

Still, the U.S.-led coalition said it expects “difficult fighting” in the days ahead to completely oust IS from the city and secure it. SDF and U.S. officials said the remaining militants are mostly suicide bombers who only have small arms and rifles. With a small area remaining, they have no access to their weapon of choice, car bombs, said Bali, the SDF spokesman.

“Our forces are waging the final phase of the battle of the presence of 'Daesh' in Raqqa. We have not decided if this battle will last hours, days or weeks,” Bali said, using the Arabic name for ISIS.

Militants seized Raqqa in 2014, the first city to fall under the full control of the extremist group. It became synonymous with ISIS’ reign of terror, with public killings and beheadings — videotaped slayings that have shocked the world. It was also from Raqqa, which became a destination for foreign fighters from around the world, that many of IS’ attacks in the West were plotted.

The latest battle for Raqqa began in June, with heavy street-by-street fighting amid intense U.S.-led coalition airstrikes and shelling. The battle has dragged on in the face of stiff resistance from the militants and civilians trapped in the city.

On Saturday, the SDF said they seized the al-Nahda neighborhood in Raqqa’s western sector. A day earlier, ISIS carried out an offensive on SDF forces near the city’s main hospital, an ISIS fortified headquarters.