Geneva - Representatives of Syria's warring factions met for talks in the same room at the United Nations on Saturday, signaling the start of the first serious effort to bring peace to Syria since Arab spring protests three years ago propelled the country into a devastating civil war.

It was a modest beginning for a process that could last many months if it is to succeed in ending the bloody conflict - or could just as easily founder fast on the intractability of the two sides and the enormity of their differences.

The rival delegations met twice, in the morning and the afternoon, in sessions at the United Nations' sprawling headquarters in Geneva headed by the U.N. special envoy, Lakhdar Brahimi. The delegates entered and left through separate doors and did not speak to one another directly, but rather relayed their comments through Brahimi, a veteran mediator of many wars who was seated between them.

"We didn't achieve much," Brahimi bluntly told reporters at the end of the day. "We are moving not even in steps, but in half-steps."

Brahimi said he hoped these first sessions, scheduled to continue today, will lead to an agreement to allow food to reach starving residents besieged by government forces in the center of the city of Homs.

The Homs negotiations are intended, however, only as a "prelude" to discussions on the far tougher issue of forming a transitional government that would take power away from President Bashar Assad's regime, Brahimi said.

"If we achieve success on Homs we hope this will be the beginning to discuss other issues," he added.

The question of what the real issues are plunged the peace effort into difficulty even before it had begun, with the opposition refusing to attend the first day of talks Friday because the government had not accepted that their chief purpose was to negotiate a transition of power from Assad.

The issue also underpins the Syrian war, which has raged unchecked since peaceful demonstrations aimed initially at reforming Assad's regime evolved into armed rebellion in response to the government's efforts to crush the protests with force.

The Syrian government says it has come to Geneva to channel international support for its efforts to fight terrorism, citing the rising influence of the al-Qaida-linked factions that hold increasing sway over swaths of rebel-held territory in northern Syria.

The opposition, however, insists it has agreed to attend the talks only on condition that they focus on a transition of power under the terms of the international agreement known as Geneva I that was negotiated in June 2012 between Russia and the United States.

Syria's information minister, Omran al-Zoubi, told reporters Saturday that the government still has "complete reservations" regarding the formation of a transitional government.

"Syria is a state with institutions," he said. "A transitional governing body . . . happens where the state is in disintegration, or has no institutions."

According to diplomats, his comments reflected in part sensitivities over language that need to be navigated by Brahimi, 80, who has brokered discussions on transitional governments in Afghanistan and Iraq, among other places.

But it is also unclear whether Syria's government is prepared to negotiate any form of transition that would loosen the Assad family's 40-year hold on power. The opposition, which was deeply divided over whether to attend at all, is under pressure from its constituency to demonstrate that it is making progress on replacing Assad.

In one possible sign of the government's misgivings about the talks, the most senior members of its delegation stayed away from Saturday's sessions. Foreign Minister Walid al-Moualem, the head of the delegation, as well as Zoubi, Deputy Foreign Minister Faisal Mekdad and presidential adviser Bouthaina Shaaban, did not attend. The government delegation was headed by Syria's ambassador to the United Nations, Bashir al-Jaafari.

A U.S. official in Geneva, speaking on the condition of anonymity because of the sensitivity of the subject, said the failure of the top officials to attend demonstrates "that they do not represent the best interests of the Syrian people, who deserve real negotiations to end the war and the suffering."

However, Brahimi and officials traveling with the government delegation said the top members had refrained from attending Saturday's sessions only because the head of the opposition's delegation, Ahmad al-Jarba, also did not attend.

Louay Safi, spokesman for the opposition delegation, described Saturday's sessions as "introductory discussions" and said that real negotiations on a new government would begin Monday.

But with the regime delegation making it clear that it is not yet ready for discussions on a new government, it is far from certain that the subject will be broached so soon. Brahimi said only that he had advised both sides not to talk too much to the press.