* Islamic Front reject peace talks
* Activists say Assad using barrel bombs in Aleppo
* 194 killed on Saturday - monitoring group
* Both sides pressured to give concessions at talks
By Oliver Holmes
BEIRUT, Jan 19 (Reuters) - A powerful alliance of Syrian Islamist rebels rejected upcoming peace talks on Sunday, meaning that even if the talks reach an unlikely breakthrough in the three year old civil war, it will be harder to implement it on the ground.
Syria's main political opposition group in exile, the National Coalition, agreed on Saturday to attend the talks beginning on Wednesday in Geneva, setting up the first meeting between President Bashar al-Assad's government and its foes.
But the Islamic Front, an alliance of several Islamist fighting forces that represents a large portion of the rebels on the ground, said on Sunday it rejected the talks.
Syria's future would be "formulated here on the ground of heroism, and signed with blood on the front lines, not in hollow conferences attended by those who don't even represent themselves," Abu Omar, a leading member of the Islamic Front, said on his Twitter account.
Some 130,000 people have been killed and a quarter of Syrians driven from their homes in the civil war, which began with peaceful protests against 40 years of Assad family rule and has descended into a sectarian conflict, with the opposing sides armed and funded by Sunni Arab states and Shi'ite Iran.
SOME AID REACHES BESIEGED AREA
In what appeared to be a symbolic conciliatory move ahead of the talks, Syria permitted some aid to reach a besieged suburb of Damascus on Saturday and Sunday, state media said.
Saturday's shipment included only 200 food parcels for Yarmouk, a camp of Palestinian refugees where 15 people have died of malnutrition so far under a seven-month siege. U.N. Relief Works Agency spokesman Chris Gunness said it would feed just 330 of the camp's 18,000 residents for a month. It was not immediately clear how much aid made it through on Sunday.
Cold War foes Moscow and Washington, which have emerged as the leading pro- and anti-Assad powers, have urged both parties to make concessions, including ceasefires, access for aid and prisoner exchanges, to build confidence before the conference.
Russian news agency Itar-Tass cited Deputy Foreign Minister Mikhail Bogdanov as saying that the opposition Coalition had made "a correct decision" in agreeing to attend.
"We have been saying the entire time that it is necessary to go to the forum and enter into dialogue with the government."
Syrian Foreign Minister Walid al-Moualem, on a visit to Moscow this month, said he had given Russian officials a plan for a truce in Aleppo, Syria's biggest city, and said the government was ready to swap lists of prisoners to be freed.
But there is little sign of violence abating or of either side winning a final victory on the battlefield.
Activists around the country, from the capital to Aleppo to the eastern province of Deir al-Zor on the border with Iraq, said that the Syrian air force was using jets and helicopters to bomb rebel-held areas.
Rebel fighters from Syria's Qalamoun mountain range, near the border with Lebanon, said more than 60 opposition militants had been killed in an ambush by forces loyal to Assad on Sunday.
The Syrian Observatory for Human Rights, an anti-Assad monitoring group, said that helicopters over Aleppo were using crudely-made and inaccurate "barrel bombs", which can collapse entire apartment blocks. It said 194 people had been killed on Saturday. Death tolls on such a scale have become almost routine as fighting has intensified in the past year.
After two years when Western countries believed Assad's days were numbered and rebels seized whole swathes of the country, the past year has seen the war largely go the president's way.
Rebels have fought each other, with groups turning against a powerful al Qaeda-linked Islamist faction. Assad's forces have recovered lost ground, and the rise of Islamists among the rebels has cost them Western support.
A last-minute decision by Washington in September to scrap plans for strikes to punish Assad for using chemical arms effectively ended more than two years of speculation that the West might join the war against Assad, as it did in 2011 against Libya's Muammar Gaddafi.
Russia's Interfax news agency reported on Sunday that Assad had told Russian lawmakers he would not yield power. Syrian state media denied the quotes as "not accurate", however.
It was not immediately clear why Damascus would object to a Russian agency reporting the president's defiant line. State media said later on Sunday that Assad had met Russian religious leaders and parliamentarians and called for an international effort to fight "terrorists", the label Damascus uses for the armed opposition. (Editing by Peter Graff; Additional reporting by Thomas Grove in Moscow)