Islamic State has released 22 of the dozens of Assyrian Christians it abducted from villages in northeastern Syria earlier this year, a monitoring group said on Tuesday.

It was not clear how many Assyrians remain in the hands of the ultra-hardline Islamist militants, but Rami Abdulrahman, head of the Britain-based Syrian Observatory for Human Rights, said they continued to hold more than 150.

The group seized more than 200 Assyrians in February when its fighters overran more than a dozen villages inhabited by the ancient Christian minority near Hasaka, a northeastern city mainly inhabited by Kurds.

The head of a Syrian Assyrian group in Sweden, Afram Yakoub, confirmed the release and said all of the freed captives were elderly men and women.

Abdulrahman said a ransom has been paid but Yakoub denied it.

¡°Some have health issues, so we believe they released them because of health issues and because they are old,¡± Yakoub, chairman of the Assyrian Federation of Sweden, told Reuters by telephone.

¡°The release is a small sign of hope. It gives us some hope that some day those remaining will be released.¡±

In March, the group released 19 of the captives.