Russia is reinforcing a military airport in central Syria as a new base for its warplanes as government forces edge closer to Palmyra, a military source and monitoring group said Thursday.
"The preparation phase for the Shaayrat base is nearing its end. It is being prepared to become a Russian military base," the military source told AFP, declining to be named.
"A number of Russian advisors arrived in Shaayrat weeks ago," the source said. The base "will begin being used by Russian forces before the end of this month".
Since Moscow began air strikes in Syria on September 30, its Su-34, Su-24, Su-30 and Su-25 planes have operated out of Hmeimim base in the coastal province of Latakia.
Shaayrat lies in Syria's central Homs province, north of several towns where government forces and allied militia backed by Russian air strikes have been fighting the Islamic State jihadist group.
Late last month, regime forces recaptured the town of Maheen after IS had overrun it on November 1.
Government troops have fought to edge closer to the historic town of Palmyra, about 130 km (80 miles) east of Shaayrat and held by IS since May.
Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, said Russia was "building new runways at the Shaayrat airport and reinforcing its surroundings in order to use it soon for operations" in Homs province.
Abdel Rahman said Russian helicopters were already using the nearby T-4 military airport to strike IS targets in Palmyra.
"Syrian regime forces are about three kilometres (less than two miles) from Palmyra and are advancing from the south and west with air cover by Russian helicopters," he said.
The troops have also reached the edges of Al-Qaryatain, a mixed Christian-Muslim village in Homs province that IS seized in August.
The military source said Russian and Syrian aircraft had conducted at least 40 strikes in and around Al-Qaryatain in the past 24 hours.
He said there would be "an important advance" within 72 hours.
Russian President Vladimir Putin pledged to intensify his country's fight against IS after the organisation's Egypt affiliate claimed to have shot down a Russian airliner carrying 224 passengers.
Starting on October 7, Syria's army launched ground attacks with Russian air support in at least four provinces across the country.
The army has also advanced in parts of Aleppo province of northern Syria.