OKEIRBAT, Syria (AP) — Government troops and their allies intensified an offensive Friday against Islamic State militants in central Syria, trying to consolidate their control on the area.

The Syrian troops and Russian military police patrolled the dusty and desolate streets of Okeirbat, which was recaptured from the extremists on Sept. 2.

A militant counteroffensive was crushed Thursday amid intense Russian airstrikes. Distant thuds of artillery were heard in Friday afternoon and evening, indicating the persistence of the fighting.

The militants had controlled Okeirbat since 2014, and Russian military officials showed visiting journalists a bombed-out warehouse that was used by the extremists to repair and fortify tanks in the once-thriving town of 10,000 people, the largest held by IS in Hama province.

The fight for Okeirbat, which lies on a strategic route linking western Syria to IS strongholds in the east, reflects the group's desperation to retain its presence in Hama province in central Syria.

It also shows the determination of the government of President Bashar Assad to uproot the group from the area, which had been a launching pad for attacks.

The Russian military has provided extensive air cover for Assad, Moscow's longtime ally, in the civil war. It sought to portray the capture of Okeirbat as a major breakthrough, helping an offensive in which Syrian government forces broke a siege by IS militants on the strategic city of Deir el-Zour only two weeks ago.

"Their defeat here helped to carry out the offensive on Deir el-Zour, reach the Euphrates River and break the siege and liberate Deir el-Zour," said Lt. Gen Alexander Lapin, chief of staff of the Russian forces in Syria.

"All the conditions are in place for the final stage of defeating IS in the western and eastern corners of Syria," Lapin told a group of international reporters brought to Okeirbat on a tour organized by the Russian Defense Ministry. He spoke while standing on a dusty street next to a building with IS slogans written on the walls of what used to be an Islamic law court.

After Assad's troops besieged Okeirbat in mid-August, a Russian missile strike on Aug. 29 destroyed the tank factory, which had been in operation since 2015 providing armored vehicles for suicide missions, Lapin said. Extremist leaflets and ammunition crates still sat on the factory floor.

The militants also had an extensive network of underground tunnels, some of them 800 meters (nearly a half-mile) long.

"The town was prepared for a siege and had a network of underground bunkers, and the Syrian army was fighting the militants for practically every house," Lapin said, adding that the population had dwindled to 2,500, all of whom fled by the time the town was recaptured.

More than two weeks of fighting in central Syria has left hundreds dead on both sides, the Britain-based Syrian Observatory for Human Rights said. The extremists still hold some villages around it and fighting still continues there.

The area is important because it is near villages loyal to Assad. Earlier this week, the extremists shelled the government stronghold of Salamiyeh that is home to members of the minority Ismaili sect, a branch of Shiite Islam.

Okeirbat was the last stop on the media tour, designed to show the strength of Russia's role in Syria, including its naval and air power. But the Defense Ministry also highlighted Moscow's humanitarian role in providing basic assistance and security for residents returning to towns recaptured in the civil war, now in its seventh year.

Backed by Russian warplanes and fighters from Iranian-backed militias, the Syrian government has enjoyed a series of battlefield successes in recent weeks. It has seen an increase in the territory it controls from a low of only 19 percent of the country earlier this year to currently about 48 percent, according to the Observatory.

Following a series of local cease-fires that were negotiated by Russia since May, Syrian and allied troops went on the offensive against IS militants as well as some U.S.-backed fighters, the Observatory said. This thrust the Syrian government into the battle against IS, raising the pressure on the militants. They now control only about 12 percent of Syria, down from about 39 percent months ago, it added.

Also on Friday, a newly negotiated "de-escalation zone" in the mostly rebel-held province of Idlib was announced during talks in Astana, the capital of Kazakhstan.

Alexander Lavrentiev, Russia's representative at the talks that are co-sponsored by Turkey and Iran, said 500 soldiers from Russia, Turkey and Iran will probably be deployed to observe and control Idlib, although details are still being worked out. The province is largely controlled by al-Qaida-linked militants and is home to nearly 1 million internally displaced Syrians.

In eastern Syria, government forces kept up their offensive on the city of Deir el-Zour, capturing a new neighborhood from IS and increasing their hold to over 60 percent of the city.

If the offensive in central Syria quells the remaining militants, it would mean IS will be mostly left in the eastern province of Deir el-Zour as well as a third of the northern city of Raqqa, once the group's de facto capital.

The Russian-backed offensive in eastern Syria is complicated by a separate and simultaneous campaign of Syrian opposition fighters backed by the U.S.-led coalition. The coalition spokesman said there are no plans to enter Deir el-Zour, indicating there will be no clash over who controls it.

Syrian government forces have been marching from western parts of the city while U.S.-backed fighters of the Kurdish-led Syrian Democratic Forces have been approaching from the north. Mohammed Ibrahim Samra, governor of Deir el-Zour province, said basic services have been restored and a hospital has been reopened.

Maj. Gen. Igor Konashenkov, a spokesman for the Russian Defense Ministry, said there are still IS fighters on the west bank of the Euphrates River in Deir el-Zour, but most have fled to the east bank.

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An Associated Press reporter in Deir el-Zour, Syria, and Sarah El Deeb in Beirut contributed.