DAMASCUS — Syrian government forces backed by Russian airstrikes advanced swiftly in central Syria on Wednesday, seizing high ground around Palmyra and positioning themselves to recapture the historic town held by the Islamic State group.

The troops, supported by Lebanese Shi’ite militiamen, reached to within 2 miles of the town, according to the state TV broadcaster. In Lebanon, the militant Hezbollah group’s television station broadcast footage of the troops, advancing through a desert landscape as helicopter gunships provided cover.

Recapturing the town would be a significant victory for the army and its Russian allies. Russia withdrew most of its forces and aircraft from Syria last week after a months-long bombing campaign that succeeded in turning the tide of the war again in the favor of Syrian leader Bashar Assad.

However, Moscow said it was keeping its bases in Syria and would continue to carry out airstrikes against the Islamic State group and other extremists.

Palmyra, a UNESCO World Heritage Site affectionately known by Syrians as the ‘‘bride of the desert,’’ has been in the hands of the Islamic State group since capturing it last May. The seizure signified a major coup for the militants.

They 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.

The advance on Palmyra comes against the backdrop of Syrian peace talks underway in Geneva between representatives of the Damascus government and the Western-backed opposition. The talks have been boosted by a Russia-US-brokered cease-fire that has mostly held since late February. The Islamic State group is not part of the truce.

Associated Press