(Adds chemical weapons spat, paragraphs 2-3, Moualem, 9-10)
* No progress on any issue towards ending civil war
* Government not committed to return on Feb. 10
* U.N. disappointed that aid has not reached Homs
* US, Russia clash over pace of Syrian chemical arms removal
GENEVA, Jan 31 (Reuters) - A contentious week-long first round of Syrian peace talks ended on Friday with no progress towards ending the civil war and the government delegation unable to say whether it will return for the next round in 10 days.
Complicating matters further, the United States and Russia clashed over the pace of Syria's handover of chemical arms for destruction with Washington accusing Damascus of foot-dragging, putting the plan 6-8 weeks behind schedule - and Moscow - President Bashar al-Assad's big power ally - rejecting this.
U.S. Secretary of State John Kerry said Syrian authorities had no excuse for delays in shipping its poison gas arsenal abroad under a deal reached last year. Moscow said Assad was acting "in good faith" and a June 30 deadline for eliminating the chemical agents remains viable.
U.N. mediator Lakhdar Brahimi, who has tirelessly pursued a peace deal that other diplomats consider "mission impossible", said the opposition delegation would be back on Feb. 10, but President Bashar al-Assad's delegates had told him they would have to check with Damascus before agreeing to return.
"They didn't tell me that they are thinking of not coming. On the contrary, they said that they would come but they needed to check with their capital," Brahimi told a news conference.
Brahimi listed 10 simple points that he felt the two sides agreed on in the talks and said he thought there was more common ground than the sides recognised.
But neither side has budged an inch from their main positions: the opposition wants the talks to focus on a transitional administration it says will remove Assad from power; the government wants to talk about fighting "terrorism" - a word it uses to refer to all its armed foes.
"Progress is very slow indeed, but the sides have engaged in an acceptible manner," Brahimi said.
Foreign Minister Walid al-Moualem blamed the lack of tangible results on what he called the immaturity of the opposition delegation and their "threats to implode" the talks, as well as blatant U.S. interference.
He said there was no pressure on his delegation from Russia, a key ally, but there was coordination between Damascus and Moscow.
Expectations had always been low for a breakthrough on political issues at the talks, the first between Assad's representatives and his foes in an almost three-year-old conflagration that has killed 130,000 Syrians and driven a third of the population from their homes.
The sides also failed to achieve more modest aims, such as an agreement to allow aid convoys into Homs, Syria's third largest city, where thousands of civilians are trapped with no access to food or medicine.
"Homs was extensively discussed, although unfortunately there has been no breakthrough yet," Brahimi said.
Underscoring the relentlessness of the carnage, the Syrian Observatory for Human Rights, a Britain-based monitoring group, said 1,870 people had been killed during the week of talks, including 450 civilians and 40 who died from inadequate access to food and medicine in areas besieged by government troops.
With few achievements on substance, diplomats say the priority now is just to keep the talks process going in the hope that hardline positions can be modified over time.
Brahimi inherited the arduous challenge of convening talks from former U.N. Secretary-General Kofi Annan, who quit in 2012 saying the job was impossible as long as global powers were at odds. Since then, the task has only grown more difficult and the war more violent.
Assad's forces have recaptured territory, reducing pressure on him to compromise. Western countries who once held out the threat of intervening against him abandoned plans for strikes last year. The rebels have become increasingly divided and Islamic militants have gained power on the ground; they refused to attend the talks.
The United Nations invited Assad's main Middle East ally Iran at the last minute, then reversed and revoked the offer.
The talks began with hardline speeches at a conference last week and repeatedly seemed on the verge of collapse before the two sides even entered the same room. Just getting them there was deemed an achievement.
Still, the sides took a first tentative step forward on Wednesday by agreeing to use a 2012 document as a basis for discussions. Thursday's final negotiating session began with a rare gesture of harmony when all sides observed a minute's silence for the 130,000 people killed during the war.
"All stood up for the souls of the martyrs. Symbolically it was good," opposition delegate Ahmad Jakal told Reuters.
CHEMICAL WEAPONS DELAY
Last year saw Washington abandon plans for strikes to punish Damascus for using chemical weapons, ending more than two years of speculation that the West might join the war against Assad as it did against Libya's Muammar Gaddafi in 2011. Instead, Assad agreed to give up his poison gas stocks, a complicated process that has fallen behind schedule.
Reuters reported on Wednesday that Syria had given up less than 5 percent of its chemical weapons arsenal and will miss a deadline next week to send all toxic agents abroad for destruction.
"The United States is concerned that the Syrian government is behind in delivering these chemical weapons precursor materials on time with the schedule that was agreed to," U.S. Defence Secretary Chuck Hagel said on Thursday.
Russia rejected the U.S. accusations and blamed security on the road to the Mediterranean coast for the delays.
"We see that the Syrians are approaching the fulfilment of their obligations seriously and in good faith," Russian Foreign Ministry official Mikhail Ulyanov was quoted as saying by Interfax news agency. "Our American partners, in their usual manner, are betting on pressure even in those cases where there is absolutely no need for it."
(Reporting by Khaled Yacoub Oweis and Stephanie Nebehay in Geneva; Additional reporting by Mariam Karouny in Geneva, Oliver Holmes and Stephen Kalin in Beirut, Missy Ryan in Warsaw and Steve Gutterman in Moscow; Editing by Peter Graff and Mark Heinrich)