Syrian rebel commander issues deadline DAMASCUS, Syria, May 31 (UPI) -- A Syrian rebel leader said his forces will leave a cease-fire agreement with the government Friday if President Bashar Assad fails to abide by truce's terms. In an Internet posting, Free Syrian Army Colonel Qassim Saadeddine set a deadline of noon Friday (local time) for Assad to begin carrying out commitments his government made to the six-point peace plan developed by U.N.-Arab League envoy Kofi Annan, Voice of America reported. If Assad fails to comply, Saadeddine said his forces no would no longer be bound by the peace plan, which has been tenuous since it went into effect in mid-April. Despite agreement to the truce, the fighting has continued, with each side accusing the other of breaking the cease-fire. The Free Syrian Army is a loosely organized and armed rebel group made up mainly of Syrian military defectors. Susan Rice, U.S. Ambassador to the United Nations, said Wednesday if Annan's plan keeps faltering, the international community must consider new ways to pressure Assad, such as sanctions and taking "actions outside of ... the authority" of the U.N. Security Council. Rice spoke after she and other Security Council members were briefed on the Syrian crisis by Annan's deputy Jean-Marie Guehenno and U.N. peacekeeping chief Herve Ladsous. Diplomats said the briefings included details of recent atrocities against Syrian civilians. Guehenno, who briefed the diplomats from Geneva, told reporters the Security Council must have a "strategic discussion" on how to prevent Syria from sliding into a "catastrophic" full-scale civil war and be united in pushing for a "political process" to resolve the Syrian conflict. Permanent Security Council member Russia repeatedly blocked the panel from taking punitive action against the Assad government, a longtime Russian ally and trade partner. Russian presidential spokesman Dmitry Peskov said Wednesday Moscow won't yield to foreign pressure to change its policy. White House spokesman Jay Carney said Wednesday supporting the Assad government was similar to putting a nation "on the wrong side of history." He said Assad "will be remembered forever for what he did this past weekend and what he has done for the past 15 months," referring to a massacre in Houla Friday in which 108 citizens died. A Syrian commission probing the civilian slaughter likely will release its findings Thursday, Syria's U.N. envoy said. The White House said President Obama discussed the Syrian crisis in a video conference with French President Francois Hollande, German Chancellor Angela Merkel and Italian Prime Minister Mario Monti Wednesday, VOA said. A White House spokesman said the leaders "shared their perspectives on the importance of ending the violence of the [Syrian] government against its own people and the urgency of achieving a political transition." Rights groups estimate that about 13,000 people have been killed in Assad's crackdown on the pro-democracy uprising since it began March 2011. The Syrian government blames the revolt on foreign-backed terrorists. Britain and other European Union countries planned to push the U.N. human rights council -- holding an emergency meeting on the massacre Friday in Geneva, Switzerland -- to demand an independent investigation, complete with forensic experts, the British newspaper The Guardian reported Thursday. U.N. cease-fire monitors reported discovering another massacre. The U.N. Supervision Mission in Syria said it discovered the bodies of 13 electrical workers Tuesday in the eastern Deir Ezzor province.