GENEVA — Syrian government and opposition delegates said talks to end their country's civil war have reached an impasse, with the United States and Russia backing the rival camps and trading accusations over the deadlock.

An opposition spokesman said Friday that after five days of negotiations the talks reached a "dead end" because of the government's "belligerence," while Syria's deputy foreign minister said the opposition came to the table with an "unrealistic agenda."

However, both sides kept the door open for more negotiations, saying the talks may continue for another day.

The deadlock and accusations underscored just how far out of reach a political solution for Syria's civil war remains. It also demonstrates the clashing interests that go beyond Syria's borders to the warring sides' international sponsors — Russia and the United States — which both have their own interests in pushing the negotiations.

Some credit the talks, now in their second round in Geneva, with leading to an evacuation of hundreds of civilians from the embattled Syrian city of Homs. But other than that they yielded little more than acrimony.

That's largely because the Syrian delegates have a fundamentally different interpretation of what the talks are about.

The opposition wants the negotiations to focus on the formation of a transitional governing body that would administer the country until the next elections, while the government says the priority is for halting "terrorism."

Meanwhile, violence has escalated in Syria, with both sides blaming each other for a soaring death toll in a conflict that has killed more than 130,000 people and displaced millions in three years.

Louay Safi, a spokesman for the Syrian opposition delegation, told reporters "the negotiations are not moving toward a political solution," accusing the government side of "belligerence." He urged all parties, particularly the Russians who are the Assad government's biggest ally, to exert pressure on the government to break the deadlock.

There has been no response, Safi said, to the proposal his side submitted Wednesday for ending the civil war, but added that the two sides might meet again Saturday for a final session before breaking up.

The opposition insists that Syrian President Bashar Assad step down, but it also has signaled a willingness to allow for concessions. On Wednesday, the opposition delegation submitted a paper to U.N. negotiator Lakhdar Brahimi that contains its vision for a post-war Syria that surprisingly omitted any mention of Assad.

However, on Friday, Safi said, "Unfortunately we have reached a dead end" in the talks. He adding that he hopes Russia and the U.S. will exert enough pressure to change that.

"I deeply regret to say that this round did not achieve any progress," Syrian Deputy Foreign Minister Faisal Mekdad said. "We came to Geneva conference to implement Syria's declared position to reach a political solution. ... Unfortunately the other side came with another agenda, with an unrealistic agenda."

He said those who claim to represent Syrians should be committed to stopping the bloodshed in the country above all else.

Earlier Friday, Russian Foreign Minister Sergei Lavrov accused the United States of using the talks for the sole purpose of "regime change," while U.S. Secretary of State John Kerry suggested Moscow was backtracking on earlier commitments.

"The only thing they want to talk about is the establishment of a transitional governing body," Lavrov said. "Only after that are they ready to discuss the urgent and most pressing problems, like terrorism," he added, speaking after meeting with the German foreign minister in Moscow.

Kerry said, who was in Beijing, said that agreeing on a transition government was the sole purpose of the Geneva talks. He said Lavrov had stood up beside him several times when Kerry had said that was the goal.

"There is no question about what this is about, and any efforts to try to be revisionist or walk back or step away from that frankly is not keeping work or keeping faith with the words that have been spoken and the intent of this conference," Kerry said.

Lavrov said the Russian-American initiative for the talks in Geneva clearly said they must not have artificial time constraints or deadlines.

"Now they are saying that to keep talking is senseless because the government (of Syria) doesn't want to agree about the makeup of a transitional governing body. We are going in circles," Lavrov said.

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Associated Press writer Mathew Lee in Beijing contributed to this report.