G8 leaders have denounced violence by Yemen's troops in response to peaceful protests across Yemen, urging President Ali Abdullah Saleh to stop the fighting and keep his commitment to end his 33-year rule.  "We urge President Saleh to immediately follow through on his commitments and ensure that the legitimate aspirations of the Yemeni people are addressed," the G8 group said on Friday after a two-day summit in France. Tribal fighters fought troops loyal to Saleh overnight in Sanaa, killing more than 40 and raising the threat of a civil war. On Friday, government planes bombed at an army camp outside the capital killing three tribal fighters. Sheik Ali Saif, a tribal leader, said his tribesmen took over the camp of the Republican Guard in the al-Fardha Nehem area, 80km north-east of Sanaa. On Thursday, hundreds of residents were fleeing Sanaa, rushing to fasten possessions to the roofs of cars, in the hope to escape the violence that has killed more than 70 people since Monday, Reuters news agency claimed. The fighting, pitting Saleh's security forces against members of Yemen's most powerful Hashid tribe, led by Sheikh Sadiq al-Ahmar, was the bloodiest the country has seen since the start of protests in January. President Saleh ordered the arrest of al-Ahmar following the deadly clashes. On Thursday, Yemen's defence ministry said Saleh had ordered that al-Ahmar and nine brothers be brought to justice for "armed rebellion". Dozens of people were killed in overnight gun fights in Sanaa, while the defence ministry said at least 28 people were killed in an explosion at an arms storage area. The headquarters of an opposition television station were"destroyed", a government official said without giving details. The latest fighting comes a day after Saleh withdrew for the third time from a deal mediated by Gulf Arab neighbours for him to quit and make way for a unity government. Pressure has been increasing since hundreds of thousands started protesting in February to call for Saleh to go, inspired by democratic revolutions in Tunisia and Egypt. The attempts by Yemen's President to stop the protests by force have so far claimed the lives of more than 200 people. The coalition of opposition parties, that have sided with protesters and was due to sign the deal brokered by GCC, held an emergency meeting on Thursday. "We call on President Saleh to stop the fighting and answer the demand of the Yemeni people for an immediate and urgent abdication of power," a statement issued by the the coalition said. On Wednesday, Saleh had said he would make no more concessions to those seeking his departure.