Islamic State has released two Syrian women and four children whom the extremist group had kept as hostages since July, said a war monitor on Saturday.

The six were among 27 people kidnapped in July in attacks by Islamic State on Syria's southern province of Sweida that left more than 200 people dead, the Syrian Observatory for Human Rights said.

The release of the first batch of hostages comes as part of a deal between the Syrian government and Islamic State, the Britain-based watchdog added. The Syrian government, in return, will release 60 women held by authorities and pay 27 million dollars, it added.

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On July 25, Islamic State staged coordinated attacks on the city of Sweida and nearby villages, killing more than 200 people, including many civilians, and taking some women as hostages.

Sweida Governor Amer al-Ashi was quoted by the official SANA news agency Saturday, saying that the release of the six abductees came due to the siege imposed on Islamic State by the Syrian armed forces on Sweida.

He added that the other abductees will be freed soon.

Islamic State and its affiliate Khaled Bin Al Waleed still control pockets north-east of Sweida. The groups also control some western areas, close to the Israeli-occupied Golan Heights.