By Khalil Ashawi
AZAZ, Syria (Reuters) - A renewed drive by President Bashar al-Assad to recapture rebel-held territory in Syria's northwest sparked a fresh exodus of many thousands of civilians toward Turkey's border on Monday amid heavy air strikes, aid workers and witnesses said.
Syrian government forces backed by Russian air power have stepped up a campaign to recapture Idlib province, the last rebel stronghold where millions took refuge after fleeing other parts of Syria earlier in its nearly nine-year civil war.
The Syrian Observatory for Human Rights, a war monitor, said Assad's forces had since Friday wrestled control of 22 towns and had cut through a strategic highway in Idlib that links the capital Damascus to Aleppo in northern Syria.
It said the Syrian army had encircled and was close to capturing Maarat al-Numan, an urban center 33 km (20 miles) south of Idlib city. This would mark a significant advance for Assad's drive to take back all of Syria.
A rescue worker who posted a video from Maarat al-Numan said the city had been devastated by an assault of barrel bombs, missiles and shelling in recent days that had laid waste to scores of homes and vital infrastructure.
"Marat al-Numan is completely destroyed and its population has been displaced and is living in uncertainty," said the civil defense force worker, who did not identify himself.
Moscow and Damascus say they are fighting jihadist militants that have stepped up attacks on civilians in Aleppo, but rights groups and rescue workers say air strikes have demolished hospitals, schools and other civilian areas.
The renewed fighting comes despite a Jan. 12 ceasefire deal between Turkey and Russia, which back opposing sides of the conflict.
Fouad Sayed Issa, an aid worker with the Violet Organization in northern Syria, said Assad's latest campaign has frightened Syrians in the rebel enclave who fear death or arrest if their towns are recaptured.
"Over the past few days we have seen thousands of new internally displaced persons and we are talking here at the very least about 50,000 over the past four days," said Issa.
A witness said that thousands on Monday fled from the Idlib towns of Ariha and Saraqib, with trucks and cars seen crawling in gridlocked traffic toward areas, including the town of Azaz, close to the Turkish border.
The Observatory estimated that about 120,000 people had fled from countryside around Aleppo and Idlib over the past 12 days. Aid workers said most have moved to relatively safer parts of northern Syria near the Turkish frontier.
Turkey, which backs some rebel groups opposed to Assad, already hosts more than 3.5 million Syrian refugees and fears that millions more could soon cross the border.
(This story was refiled to add word "city" to headline.)
(Reporting by Khalil Ashawi; Writing by Eric Knecht; Editing by Mark Heinrich)