DAMASCUS — Syrian government forces pushed Thursday into the ancient town of Palmyra, where Islamic State militants appeared on the verge of collapse.

The extremist group has been losing ground in Syria and Iraq for months under a stepped-up campaign of US-led and Russian airstrikes, as well as ground assaults by multiple forces in each country.

The retaking of Palmyra — a UNESCO world heritage site whose fall to the militants last May sent shock waves through archeological circles and beyond — would be a significant victory for the Syrian government.

The advance on Palmyra comes against the backdrop of Syrian peace talks underway in Geneva between representative of the Damascus government and the Western-backed opposition.

The talks, which have been boosted by a Russia- and US-brokered cease-fire that has mostly held since late February, adjourned on Thursday without having achieved any apparent breakthroughs.

Staffan de Mistura, the UN’s Syria envoy, set April 9 as a target date for indirect peace talks to resume in Geneva, saying he is encouraged by the fact that ‘‘no breakdowns, no walkouts’’ tripped up the latest and most substantial round of talks.

The advance on Palmyra came after government forces, backed by Russian airstrikes, managed to capture several hills and high ground around the town this week.

On Thursday, Syrian state TV broadcast footage of its reporter, embedded with the Syrian military, speaking live from the entrance of Palmyra and saying that as of midday, the fighting was concentrated near the famed archeological site on the southwestern edge of the town.

The fall of Palmyra to IS militants last year had raised concerns worldwide, and the destruction the extremists subsequently embarked upon sparked alarm and made international headlines. It was also a big blow to the government of Syrian President Bashar Assad, whose forces pulled out with little resistance.

By nightfall, intense fighting was still taking place on the outskirts. Turkey-based activist Osama al-Khatib, who is originally from Palmyra, denied that Syrian troops had entered the town, and said the video seen on Syrian state TV was taken about 3 miles from Palmyra.

Earlier in the day, Governor Talal Barazi said from the nearby city of Homs that the Syrian army was clearing roads leading into the town of mines and explosives.

‘‘We might witness in the next 48 hours an overwhelming victory in Palmyra,’’ Barazi said, adding that ‘‘the army is advancing in a precise and organized way to protect what is possible of monuments and archeological sites.’’

The Britain-based Syrian Observatory for Human Rights said Syrian troops and Shi’ite militiamen helping them on the ground were facing tough resistance from IS extremists as they try to penetrate the town’s limits.

The Observatory, which monitors the Syrian conflict through a network of activists on the ground, said IS has lost more than 200 militants since the government campaign to retake Palmyra began 17 days ago. It did not have figures for government losses.

The IS group instructed residents to leave the town Wednesday, according to a Palmyra native who asked not to be named. The town was mostly empty Thursday, save for IS fighters reported to be mining homes ahead of the advancing army.

IS militants have destroyed many of the town’s Roman-era relics, including the 2,000-year-old Temple of Bel and the iconic Arch of Triumph, and also killed dozens of captive Syrian soldiers and dissidents in public slayings at the town’s grand Roman theater and other ruins.