MONTREUX, Switzerland -- Diplomats hustled to smooth out last-minute hang-ups for this week's peace conference on Syria, playing down expectations Tuesday for a gathering thrown into confusion by a threatened opposition boycott and a refueling glitch that delayed the Syrian government delegation.
A new report emerged on Syrian regime atrocities, written by three former war crimes prosecutors who said they received thousands of photographs documenting torture and executions from a defector within the Syrian government. The report, which could not be independently verified, was commissioned by Qatar, which has been deeply involved in the conflict and is attending the peace conference.
Its emergence Tuesday appeared timed to affect deliberations at the peace conference. Participants in the talks diverge sharply on their scope, with the Western-backed Syrian opposition saying its goal was to establish a transitional government "in which killers and criminals do not participate."
International diplomats have built up the importance of the talks for weeks, insisting that there was no other way out of the war that has killed more than 130,000 people. But they have simultaneously lowered expectations for a breakthrough. Russian news agencies, citing diplomatic sources, said the talks were expected to last seven to 10 days, then take a short break.
The front lines of the war have been largely locked in place since March, and despite suffering enormous losses, neither the government nor the opposition appears desperate enough for a deal to budge from its entrenched position.
"We must take small steps," said Frank-Walter Steinmeier, the German foreign minister, citing cease-fires and humanitarian corridors.
For some of the more than 2 million Syrian refugees scattered around the region, there was little hope that the peace conference nestled in the snow-capped Alps can deliver a solution to the conflict, and scant interest in a settlement with Syrian President Bashar Assad's government.
"We lost our faith in the international community. We don't care about the Geneva conference and whether it takes place or not," said Ibraheem Qaddah, a former rebel fighter now holed up in Jordan's sprawling Zaatari refugee camp.
"We have lost a lot of relatives and friends and family members in the fighting and we've lost Syria. We are not looking for reconciliation with Bashar Assad," said Qaddah, whose left arm was amputated after he was severely wounded in the war.
The opposition Syrian National Coalition nearly quit the peace talks before they started to protest the U.N. decision to invite Iran. The invitation was retracted after the opposition's ultimatum -- a decision that came under criticism from Iran and Russia, Assad's two most powerful backers.
High-ranking delegations were arriving Tuesday from the United States, Russia and close to 40 other countries attending. Face-to-face negotiations between the Syrian government and its opponents -- the first of the uprising -- are to start Friday in Geneva.
But it's also unclear how the opposition coalition, a weak and fractured umbrella group with almost no sway over the most powerful rebel groups inside Syria, could enforce any agreement reached in Geneva.
Both sides have traded allegations of human rights violations. In the latest report of atrocities, three prominent international war-crimes experts said they had received tens of thousands of photographs documenting what they called the systematic killing of some 11,000 detainees by Syrian authorities. The images, which were smuggled out by a defector from Syria's military police, showed victims' bodies with signs of torture and maltreatment.
Assad's family has ruled since 1970, and Iran is Assad's strongest regional ally. The Islamic Republic has supplied the Syrian government with advisers, money and weapons since the uprising against his rule began in March 2011. Iran's allies, most notably the Lebanese Shiite militant group Hezbollah, also have gone to Syria to help bolster Assad's forces.
The controversy over invitations to the talks highlighted fundamental differences over Syria, which has developed into a proxy war between Iran, the region's Shiite Muslim power, and Saudi Arabia, the Sunni heavy weight. It also has played out tensions between the United States and Russia, which has shielded Assad's regime from U.N. sanctions and continued to supply it with weapons throughout the civil war.
In Moscow, Russian Foreign Minister Sergey Lavrov said U.N. chief Ban Ki-moon's decision to rescind Iran's invitation was a mistake, but that the Kremlin would try to make the Geneva negotiations work.
"There is no catastrophe. We will push for a dialogue between the Syrian parties without any preconditions," Lavrov told reporters Tuesday.
Lavrov reaffirmed Russia's stance that the presence of Iran was essential for the success of the talks, saying Tehran's absence "isn't going to help strengthen the unity of the world's Muslims."
Iran's Foreign Ministry also sharply criticized Ban's diplomatic about-face.
"From our point of view, the withdrawal is deplorable," ministry spokeswoman Marzieh Afkham said, adding that the U.N. chief must have done so under immense pressure.
The last-minute flap over Iran's participation set a chaotic tone for the run-up to the conference.
In another bizarre twist, Syrian state TV said the government delegation stopped in Athens but couldn't leave because Greek authorities weren't allowing them to refuel the plane. The delegation, led by Foreign Minister Walid al-Moallem, was ultimately cleared to leave.
The Greek Foreign Ministry said the delay was caused by two private companies who refused to refuel the plane because of Western sanctions against Syria.
-- By ZEINA KARAM and LORI HINNANT
Associated Press writers Ryan Lucas in Beirut, Vladimir Isachenkov in Moscow, Omar Akour in Zaatari Camp, Jordan, Elena Becatoros in Athens, and Ali Akbar Dareini in Tehran, Iran, contributed to this report.