A key group within the Syrian opposition National Coalition said Sunday it would not attend proposed peace talks in Geneva and would quit the Coalition if it participated.

"The Syrian National Council, which is the biggest bloc in the Coalition, has taken the firm decision... not to go to Geneva, under the present circumstances (on the ground)," Council president George Sabra told AFP.

"This means that we will not stay in the Coalition if it goes" to the peace talks in Geneva, he added.

He invoked the ongoing suffering of Syrians on the ground and said his group would not negotiate before the fall of the regime.

"The residents of Moadamiyet al-Sham are dying of hunger," he said, referring to a Damascus rebel suburb under regime fire where the Syrian Red Crescent evacuated 1,500 people on Sunday.

"Ghouta (outside Damascus) is under siege and it is forbidden to even bring in bread. Are these the conditions that will allow us to achieve... a democratic transition in Syria?" Sabra added.

The international community, led by Russia and the United States, has been pushing for the Syrian regime and rebels to attend a peace conference dubbed Geneva 2 to find a political solution to the conflict.

The proposed meeting has been delayed for months, but Washington and Moscow are now talking about a potential mid-November date for the conference.

The Syrian National Council, which is one of the most important members of the Syrian opposition, has long said it will not negotiate until President Bashar Assad's regime is toppled.

But Sabra's announcement, which comes after two days of meetings of the Council's top leadership, could deal a major blow to the planned talks.

It comes a day before U.S. Secretary of State John Kerry is due in London to meet Lakhdar Brahimi, the U.N.-Arab League envoy for Syria, to discuss preparations for the Geneva 2 meeting.

Last month, the Coalition's president Ahmed Jarba met with U.N. chief Ban Ki-Moon, who praised his "commitment to send a delegation to the Geneva Conference."

Ban also urged Jarba "to reach out to other opposition groups and agree on a representative and united delegation," U.N. spokesman Martin Nesirky said.

But the prospect of talks with Assad's regime continues to be deeply unpopular both among members of Jarba's Coalition and rebel fighters on the ground in Syria.

Sabra fiercely criticized the international community, accusing it of failing to punish the regime after an August 21 sarin attack that reportedly killed hundreds of people in the outskirts of the capital Damascus.

Washington threatened to carry out military strikes in response to the attacks, which the United States and the Syrian opposition blamed on the regime.

But military action was averted by a U.S.-Russian deal under which Syria is turning over its chemical arsenal for destruction.

"The international community has focused on the murder weapon, which is the chemical weapons, and left the murderer unpunished and forgotten the victims," Sabra said.

"The regional and international context does not give the impression that Geneva 2 will offer anything to the Syrians," he added.

"We will not participate in a conference that is intended to hide the failure of international politics."