Syria's main Western-backed opposition group has approved a partial cabinet charged with administering rebel-held territories inside Syria.

The move by the Syrian National Coalition late Monday follows its announcement earlier in the day that it plans to attend proposed peace talks with the Syrian government, if certain conditions are met.

The coalition has struggled for months to cobble together an interim government, in part because of infighting among the various exile groups involved. In votes on Monday, the coalition approved most of the cabinet, but could not agree on some positions, according to those who took part in the voting.

The opposition government is tasked with organizing governance in rebel-held areas of Syria, although its ability to fulfill that goal appears limited.

The coalition's already slim support inside Syria received a severe blow in September when nearly a dozen of the most powerful rebel factions publicly broke with the coalition. The brigades said they do not recognize any government formed outside Syria.

That announcement highlighted the growing irrelevance of the coalition and its military arm headed by Gen. Salim Idris, who leads the Supreme Military Council supported by the West, amid increasing radicalization in Syria. The group is seen by many as being out of touch and a puppet of the West and Gulf Arab states.

On Monday, a coalition of Syria-based opposition groups said that the peace conference proposed by the United States and Russia to be held by the end of the year may be the last chance to negotiate an end to Syria's civil war.

The call came as Syrian government forces consolidated control over yet another northern town, part of a steadily advancing offensive that has reversed rebel gains in recent weeks.

In Damascus, Syria's state news agency said a mortar shell hit a school bus Monday in the Bab Sharqi neighborhood, killing four children and the bus driver. It said four children and two teachers were also wounded.

“This is the only available framework and might be the last chance to resolve the crisis in Syria,” the Coalition of Forces for Peaceful Change said in a statement.

Neither that coalition nor the SNC, however, has much influence over the disparate armed factions fighting to overthrow President Bashar Assad. The Syria-based opposition ranges from officials close to the government, to intellectuals and parties that have opposed Assad's Baath party for decades. The exiled group ranges from secular intellectuals to Islamic activists.

In its statement Monday, the SNC said it would only attend the talks Geneva talks if humanitarian aid is allowed to reach besieged areas and the government releases political prisoners. The group itself wants any future transitional government to exclude Assad and his close allies, a demand the Syrian government has rejected.

The proposed Geneva conference faces a series of obstacles: the most powerful and best-armed rebel groups aren't party to the talks, and most fighting units are disorganized bands with little central command or leadership. Even if an agreement is reached in Geneva, it is unclear if it will be accepted on the ground.

As diplomats have been trying to convene peace talks, the fighting on the ground has raged on.

Government forces took over the town of Tel Aran and other positions in the northern province of Aleppo, state media said, a day after they consolidated control of a key military base held by rebels since February. The British-based Syrian Observatory for Human Rights, which receives its information from a network of activists on the ground, also reported the government advances.

The Observatory and an Aleppo activist said they believed the government's gains were partly caused by rebel infighting. The al-Qaida-linked Islamic State in Iraq and the Levant in particular, they said, was trying to drive weaker opposition groups from rebel-held areas.

In Geneva, the World Health Organization said it has now confirmed 13 cases of polio in Syria as part of the first outbreak of the highly communicable disease in the country in 14 years. The WHO also said genetic sequencing indicates the strain is closely linked to one that originated in Pakistan and was detected in environmental samples in Egypt last year.

The U.N. has launched a massive vaccination campaign across the Middle East to try to control the outbreak. (AP)