MOSCOW- Hundreds of Syrian militants have launched attacks against government forces in several parts of Syria's Idlib province, killing up to 40 Syrian soldiers, the Russian Defence Ministry said on Thursday.

The militants had seized two settlements in one of the offensives, the ministry said, saying Syrian army troops had been forced to abandon some of their positions in the southeast of the so-called Idlib de-escalation zone under rocket fire.

Idlib is the last rebel-held swathe of territory in the country and hundreds of thousands of people in the area have fled in recent weeks amid heavy air strikes by Russian and Syrian forces.

Russia, which is helping President Bashar al-Assad's forces, said Syrian government forces had killed up to 50 militants and wonded up to 90 attackers.

The attacks began on Wednesday, it said, saying some fighting was still going on. About 40 soldiers had been killed and up to 80 wounded.

Moscow said the attackers were from different groups, including the Islamic Party of Turkestan and Tahrir al-Sham, the latest incarnation of the former Nusra Front that was part of al Qaeda until 2016.

The militants were equipped with pickup trucks, armoured personnel carriers, tanks and heavy machine guns, it said.

(Reporting by Anton Kolodyazhnyy and Tom Balmforth Writing by Andrew Osborn; Editing by Alex Richardson and Angus MacSwan) ((Tom.Balmforth@thomsonreuters.com;))