Story highlights Russia, Turkey and Iran will formalize the zone boundaries by early June

A December ceasefire has been largely ignored

(CNN) A ceasefire in four zones outlined in a new Syria peace plan is scheduled to go into effect Saturday, a Russian envoy to de-escalation talks told reporters, according to state media.

The ceasefire will last six months and could be "automatically extended" for another six months, Alexander Lavrentyev said Friday after talks in Astana, Kazakhstan.

Turkey's state-run Anadolu news agency also reported on the ceasefire -- signed by Russia, Turkey and Iran -- saying a joint working group will be set up by the agreement's three guarantor countries to determine the precise borders of the four zones by June 4.

The security zones would be in place in Idlib province, to the north of the city of Homs, in Eastern Ghouta near Damascus, and in southern Syria.

Such zones, also referred to as non-conflict or safe zones, are meant to be areas where civilians can live without being targeted by any party in Syria's war. However, key issues would involve whether and how the zones would be enforced.

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