BEIRUT (AP) — Turkey, Iran and Russia have signed an agreement calling for the setting up four "de-escalation zones" in war-torn Syria in the latest attempt to reduce violence in the Arab country.

But as officials form the three countries that back rival sides in the conflict signed the agreement on Thursday at the Syria cease-fire talks in Kazakhstan, some members of the Syrian opposition delegation shouted in protest and walk out of the conference room in Astana, the Kazakh capital.

The opposition has protested Iran's participation at the conference, accusing it of being a party in the war that's killed some 400,000 people.

The Kazakhstan agreement calls for setting up four zones in northern, central and southern Syria. However, no details were provided about how violence will be reduced in these areas.