GENEVA -- Peace talks aimed at ending Syria's five-year civil war got off to a shaky and chaotic start Friday, with the main opposition group at first boycotting the session, then later agreeing to meet with UN officials -- while still insisting it would not negotiate.

That small commitment by the group known as the Higher Negotiating Committee came just minutes before UN special envoy Staffan de Mistura met with a delegation representing the government of President Bashar Assad.

The developments gave a glimmer of hope that peace efforts in Syria might actually get off the ground for the first time since two earlier rounds of negotiations collapsed in 2014.

The conflict has killed at least 250,000 people, forced millions to flee the country, and given an opening to the Islamic State group to capture territory in Syria and Iraq. It has drawn in U.S. and Russia, as well as regional powers such as Turkey, Saudi Arabia and Iran.

The HNC, a Saudi-backed bloc, had previously said it would not participate in the UN-sponsored talks without an end to the bombardment of civilians by Russian and Syrian government forces, a lifting of blockades in rebel-held areas and the release of detainees.

An HNC statement said the opposition decided to take part in the talks after receiving assurances from friendly countries about those humanitarian issues, and that a delegation headed by HNC chief Riad Hijab will leave Saudi Arabia for Geneva on Saturday.

Only once their conditions are met will they negotiate, the statement added.

De Mistura said he had "good reason to believe" the HNC would join the talks Sunday, but refused to react formally until he got an official notice from its leadership.

"As you can imagine, I have been hearing rumours and information already," de Mistura told reporters after meeting with the delegation led by Syria's UN ambassador, Bashar Ja'afari.

"What I will react to -- that's why I said I have reasons to believe -- I will only react when I get a formal indication of that," de Mistura said, "But that is a good signal."

Speaking almost simultaneously at a hotel across town, HNC member Farah Atassi told reporters its delegation would arrive Saturday only to talk to UN officials about its demands after receiving some reassurances from the UN, but "not to negotiate."

The decision came after many Western powers and Saudi Arabia -- a major backer of the group -- had pushed hard for the HNC to attend, diplomats said.

Disputes have arisen over which opposition parties will attend, with the HNC coming under criticism for including the militant Army of Islam group, which controls wide areas near the capital of Damascus, and is considered a terrorist organization by the Syrian government and Russia.

The largest Kurdish group in Syria, the Democratic Union Party or PYD, is not invited to the talks. Turkey considers the PYD to be a terrorist organization. Also not invited are the Islamic State group and the al Qaeda-linked Nusra Front.

Opposition figures from outside the HNC also are in Geneva, but they were invited as advisers.

The meetings, billed as multiparty talks, are part of a process outlined in a UN resolution last month that envisions an 18-month timetable for a political transition in Syria, including the drafting of a new constitution and elections.

De Mistura has decided that these will be "proximity talks," rather than face-to-face sessions, meaning that he plans to keep the delegations in separate rooms and shuttle in between. He has tamped down expectations by saying he expects them to last for six months.

UN spokesman Ahmad Fawzi reflected the chaos and confusion earlier in the day when he told reporters that "I don't have a time, I don't have the exact location, and I can't tell you anything about the delegation."

The initial refusal of the HNC to attend was slammed by Syria's official Tishrin newspaper as reflecting "the collective flight of terrorist groups backed by Saudi Arabia and Turkey from the political table, following their collapses on the battlefield."

Ja'afari, the Syrian envoy, declined to speak to reporters as he left the meeting with de Mistura.

Turkish President Recep Tayyip Erdogan said the moderate opposition was not attending because Russia continues to bomb rebel-held areas in Syria, and that it is a "betrayal" to the moderates to ask them to attend without a ceasefire.

Qadri Jamil, a former Syrian deputy prime minister who has become a leading opposition figure but is not part of the HNC, told The Associated Press that the priority was to allow aid into besieged areas.

A Western diplomat in close contact with the SNC said in Geneva that the HNC's "main message to us has been, 'while we are under sustained attack by Russia and the regime and other states and militants and other groups, we cannot justify to Syrians why we are going."' The diplomat spoke on condition of anonymity because he was not authorized to talk to reporters on behalf of the opposition.

Reflecting the growing outside military presence in Syria, the Dutch government said Friday it plans to join the U.S.-led coalition targeting the Islamic State group in Syria with airstrikes.

The Dutch have for months been carrying out airstrikes in neighbouring Iraq, but have balked at extending the mission to Syria. But after requests from the U.S. and France, Dutch Prime Minister Mark Rutte's two-party coalition government decided to broaden the mandate to eastern Syria.

Associated Press writers Zeina Karam in Beirut and Suzan Fraser in Ankara contributed to this report