Syrian opposition groups say they hold the Syrian government and its Russian backers responsible for any failure in peace talks due to their "ongoing crimes" in Syria including the "besiegement and starvation of civilians."

Although they affirmed their support for the political process, the groups say it is impossible to begin the negotiating process without full implementation of Security Council resolutions pertaining to humanitarian issues.

The groups include the Syrian National Coalition, the main Western-backed opposition group, as well as 44 rebel groups including the powerful Saudi-backed Jaish al-Islam, or Army of Islam.

The U.N.-sponsored peace talks were scheduled to begin Monday in Geneva but now appear to be delayed over continued divisions over who should represent the opposition at the talks.