Four of the seven relief workers who were abducted in Syria have been released, International Committee of the Red Cross spokesman Simon Schorno said on Monday.

“I can confirm they have been released,” Mr. Schorno said in Damascus, without giving details as to their whereabouts or how they were freed.

On Sunday, six Red Cross staff members and one volunteer for the Syrian Arab Red Crescent were kidnapped in Idlib, in north-west Syria.

The team had travelled to Idlib on Thursday to assess the medical situation there and were on their way back to Damascus when they were seized.

State television accused “terrorists” for the kidnapping.

The Syrian Observatory for Human Rights -- a Britain-based opposition watchdog -- said the al-Qaeda-linked Islamic State in Iraq the Levant were behind the abduction.

“The Islamic State in Iraq the Levant released rebel fighters and workers of the Red Cross who were abducted yesterday,” the observatory said in a statement.

The Red Cross said last month that 22 of its workers have been killed in Syria since the country’s conflict started in March 2011.

All the victims belonged to the Syrian Arab Red Crescent and were killed while carrying out humanitarian work, it said.

Earlier Monday, Syria officially acceded to the United Nations convention banning chemical weapons, the spokesman of the Organisation for the Prohibition of Chemical Weapons (OPCW) said.

“As of today Syria became a full-fledged state member of the convention,” Michael Luhan told dpa from the group’s headquarters in The Hague.

Around 60 members from the UN-backed OPCW is overseeing the destruction of Syria’s stockpile as well as some of its chemical weapons production equipment.

The Norwegian Nobel Committee last week awarded the OPCW the Nobel Peace Prize for “its extensive efforts to eliminate chemical weapons.” Syria is the 190th country to join the convention. Only six states have yet to sign the international treaty.

In September, Syria signed the Chemical Weapons Convention, following Russia’s proposal that it hand over its chemical weapons to international supervisors.

The Syrian regime in August was accused by Western powers and the Syrian opposition of using sarin gas in areas near the capital Damascus. The United States said the attack killed 1,400 people.

President Bashar al-Assad repeatedly denied the accusation.

Inside the country, at least 20 people were killed on Monday in a car bomb blast in the area of Darkoush, in Idlib province, the Observatory reported.

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