BEIRUT- Syrian government forces opened a corridor on Thursday for people who want to leave insurgent territory in northwest Syria, where an army offensive has gained ground, state media said.

Ten of thousands of people have fled towards the Turkish border in recent days as air and ground attacks battered parts of Idlib and Hama in the northwest, the last big rebel stronghold.

After the collapse of a brief ceasefire this month, Syrian army troops, backed by Russia, have now marched into a town in Idlib province in rebel hands since 2014.

The United Nations says hundreds of people have been killed since the offensive began in late April. More than 500,000 people have been uprooted since, it says. Most escaped deeper into the rebel bastion and towards the border, while about 30,000 have fled into government territory.

"The Syrian Arab Republic announces the opening of a humanitarian corridor in the (town) of Soran...to enable citizens wanting to exit," state news agency SANA said, citing a foreign ministry source.

It said the corridor would allow civilians to leave the southern part of Idlib and the north of Hama. The government would provide them with food, shelter and healthcare, it said.

Naji Mustafa, spokesman for the National Liberation Front rebel coalition, dismissed the opening of the latest corridor as an attempt to hit morale.

"It's impossible today for people to head towards the Syrian regime's areas. These people have escaped the regime," he said.

U.N. estimates put the population of northwest Syria at nearly three million people. Many poured into the region after fleeing fighting in other parts of Syria that President Bashar al-Assad recovered with Russia and Iran's help.

Moscow and Damascus say they are responding to militant attacks by the former Nusra Front, a jihadist alliance now known as Hayat Tahrir al-Sham. It is the dominant force in Idlib, where Turkey-backed factions also have a presence.

(Reporting by Ellen Francis in Beirut and Khalil Ashawi in Turkey; editing by Angus MacSwan) ((Ellen.Francis@thomsonreuters.com))