* Opposition demands govt first agree to transition
* UN mediator will meet delegations separately
* Kerry says Assad not ready to quit
By Khaled Yacoub Oweis and Stephanie Nebehay
GENEVA, Jan 24 (Reuters) - Syria's first peace talks faltered before they began on Friday, with opponents of President Bashar al-Assad refusing to meet his delegation unless it first signs up to a protocol calling for a transitional government.
Plans were ditched at the last minute for the two sides to sit down to talk face to face for the first time. Instead, they would each meet separately with a U.N. mediator, Lakhdar Brahimi, at the United Nations headquarters in Geneva.
The closed-door discussions were due to begin on Friday, two days after a formal opening conference was held in a poisonous atmosphere, with both sides and their global backers making uncompromising public speeches. Any direct meeting appears unlikely for now.
The opposition says it has come to discuss a transition that will remove Assad from power. The government says it is there only to talk about fighting terrorism - the word it uses for its enemies - and no one can force Assad to go.
Opposition delegates decided they would not meet the government delegation unless it endorsed "Geneva 1", a 2012 protocol that calls for a political transition.
"We have explicitly demanded a written commitment from the regime delegation to accept Geneva 1. Otherwise there will be no direct negotiations," opposition delegate Haitham al-Maleh told Reuters.
A U.N. spokeswoman confirmed Brahimi would meet the delegates separately: "There are no Syrian-Syrian talks at the moment," said Alessandra Vellucci. "I cannot tell you anything about what will happen in the next few days."
Even before the announcement that the direct talks were cancelled, the outlook was dim.
"The objective is for the first round of talks to last until next Friday, but expectations are so low we'll see how things develop day by day," a Western diplomat said.
"Every day that they talk is a little step forward."
Brahimi has indicated that his aim is to start by seeking practical steps, like local ceasefires, prisoner releases and access for international aid deliveries, before embarking on the tougher political negotiations.
Syria's civil war has already killed at least 130,000 people, driven up to a third of the country's 22 million people from their homes and made half dependent on aid, including hundreds of thousands cut off by fighting.
Among the hurdles to progress, the Islamist militants who control most rebel-held territory are boycotting the talks and say anyone attending negotiations that fail to bring down Assad would be traitors.
Assad's main regional backer, Iran, is also not represented at the Geneva talks. U.N. Secretary-General Ban Ki-moon invited Tehran at the last minute, but then withdrew the invitation 24 hours later when it refused to endorse the Geneva 1 protocol.
During Wednesday's opening ceremony, the government delegation drew a rebuke from Ban for using inflammatory language after referring in a speech to rebels raping dead women, ripping foetuses from the womb and eating human organs.
In a defiant speech on Thursday, opposition leader Ahmed Jarba said the international community had concluded that Assad cannot stay in power.
"We have started to look into the future without him. Assad and all of his regime is in the past now. Nobody should have any doubt that the head of the regime is finished. This regime is dead," Jarba said.
Moscow, a key ally for Assad, had given assurances that it was not "holding on" to the president, Jarba said.
Moscow has signed the Geneva 1 protocol calling for a political transition but says that does not necessarily mean Assad must leave power.
Assad's officials left talks with Brahimi on Thursday evening without making any statement.
U.S. Secretary of State John Kerry said there was no sign Assad was ready to quit, although he insisted the Syrian leader had no place in his country's future.
"This is a man who has committed war crimes and still somehow wants to claim legitimacy to be able to govern the country," Kerry said in an interview with Al-Arabiya television.
But Kerry said there could be a place for officials from Assad's government in a transitional government as long as they "do not have blood on their hands". (Additional reporting by John Irish, Mariam Karouny, Samia Nakhoul, Dominic Evans, Tom Miles and Gabriela Baczynska; Writing by Peter Graff; Editing by Alastair Macdonald)