BEIRUT (Reuters) - Syrian troops and allied forces seized an air base in Idlib province on Saturday, pressing their offensive into the country’s largest insurgent stronghold, state television said.

The province in northwest Syria has become a focal point of the war, with government forces taking scores of villages in recent weeks. With the help of Iran-backed militias and Russian air power, they advanced towards Abu al-Duhur military airport, where rebels had ousted the army in 2015.

Since mid-December, fighting has forced more than 212,000 people to flee their homes in the south of Idlib and nearby parts of Hama and Aleppo provinces, the United Nations says.

Ankara has warned the attacks will cause a new wave of migration, urging Russia and Iran to rein in the Syrian army offensive in Idlib, which borders Turkey.

Rebels have held Idlib since 2015, and its population has mushroomed with fighters and civilians escaping offensives in other parts of Syria. It has since become the largest single chunk of the country still under the control of factions fighting President Bashar al-Assad’s state.

Tahrir al-Sham, spearheaded by al-Qaeda’s former Syria branch, is now the dominant insurgent force in the province.

In a broadcast from outside Abu al-Duhur airport, state TV said the military was searching the base for mines and battling insurgents around it.

The Syrian Observatory for Human Rights, a Britain-based war monitor, said the army and allied militia took full control of the airport after heavy air strikes against the insurgents.

The troops had stormed the base hours earlier, said a military media unit run by Lebanon’s Hezbollah, which fights alongside the Damascus government. Other pro-government forces seized villages in rural Aleppo, it said.

The army offensive has pushed into Idlib along several fronts from rural Hama to the south and from Aleppo province to the east.

Government forces at opposite ends linked up on Saturday, splitting rebel territory in two, the Observatory and the Hezbollah media unit said. The advance besieged militants near the airport in an enclave, part of it under Tahrir al-Sham control and the other in the hands of Islamic State.

In recent weeks, Tahrir al-Sham had been simultaneously under attack at the corner of Idlib from Islamic State, which has expanded a small pocket of territory in Hama since the army ousted it from central Syria last year.