(BBC) -- Islamic State fighters have been driven out of Assyrian Christian villages in Syria that they seized in February, activists say. The UK-based Syrian Observatory for Human Rights said Kurdish fighters had retaken the villages along the Khabur river in north-eastern Syria. But some reports say Syrian government forces drove the IS fighters out. Also on Wednesday it was reported that two of the hostages seized from the villages by IS had been freed. The two elderly women arrived in the provincial capital of Hassakeh on Tuesday, activists said. About 200 people from the villages are thought to still be in IS captivity. Christians under pressure The villages were cleared of IS fighters earlier this week but many residents have not returned for fear of any remaining IS fighters and booby traps, according to Afram Yakoub, chairman of the Assyrian Federation of Sweden. Mr Yakoub said IS's retreat was largely due to an air campaign by Syrian government forces. It is estimated that up to 40,000 Assyrians lived in Syria - alongside the overall Christian population of 1.2 million - before the country's civil war broke out in 2011. The Assyrians, one of the world's oldest Christian communities, have been under increasing pressure since IS captured large parts of the country. Some 1,000 local Assyrian families are believed to have fled their homes in the wake of the abductions. line Syria's Christians

• Thought to have constituted about 30% of the population as recently as the 1920s
• Long part of Syria's elite - founder of ruling Baath party was a Christian
• Before the war made up some 10% of Syria's 22 million people
• Up to 40,000 of those were Assyrians. They speak Syriac, a form of Aramaic, the language of Christ
• Hundreds of thousands have been displaced by the fighting
• Some have taken up arms to defend themselves against Islamists