G8 leaders have condemned violence by Yemeni forces against peaceful protesters and called on President Ali Abdullah Saleh to stick to his commitment to end his 33-year rule.
"We condemn the use of violence in response to peaceful protest throughout Yemen," the G8 leaders said on Friday after a two-day summit in France.
"We urge President Saleh to immediately follow through on his commitments and ensure that the legitimate aspirations of the Yemeni people are addressed," the group said in a statement.
"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"
Yemeni opposition coalition
Tribal fighters overnight battled troops loyal to Saleh in the capital Sanaa, killing more than 40 and raising the spectre of a civil war.
On Friday, three tribal fighters were killed after government planes bombed an army camp outside the capital.
Sheikh Ali Saif, a tribal leader, said his tribesmen had taken over the camp of the Republican Guard in the al-Fardha Nehem area, some 80km northeast of the capital Sanaa.
On Thursday, residents were fleeing Sanaa by the hundreds, hurriedly fastening possessions to the roofs of cars, hoping to escape the violence that has killed more than 70 people since Monday, Reuters news agency reported.
Fighters in civilian clothes roamed some districts and machine gun fire rang out sporadically.
The fighting, pitting Saleh's security forces against members of the country's most powerful Hashid tribe, led by Sheikh Sadiq al-Ahmar, was the bloodiest Yemen has seen since protests began in January.
The Yemeni president ordered the arrest of Sheikh Sadiq following the deadly clashes.
In a statement issued 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 battles in Sanaa, while the defence ministry said at least 28 people were killed in an explosion at an arms storage area.
A government official said that the headquarters of an opposition television station had been "destroyed", without giving details.
Sheikh Sadiq is the leader of the Hashid tribe, which includes Saleh's tribe, and has been a vocal opponent of the president, joining protesters in calling for him to leave power.
The Hashid tribe is one of two main tribal groupings in Yemen. Alongside the Baqil, it has played a leading role in politics for centuries.
According to leaked US cables, Sheikh Sadiq, and his brother Amid, have long wanted to replace Saleh.
And in March, another member of the clan - Yemen army general - Ali Mohsen al-Ahmar, also threw his weight behind the protesters.
No takers for GCC deal
The most recent bout of fighting erupted a day after Saleh pulled out 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 mounting since February, when protesters inspired by democratic revolutions in Tunisia and Egypt began camping in squares and marching in their hundreds of thousands to call for Saleh to go.
His attempts to stop the protests by force have so far claimed the lives of more than 200 people.
The coalition of opposition parties that has sided with protesters and was due to sign the deal brokered by GCC held an emergency meeting on Thursday over what it called Saleh's "insistence on dragging Yemen towards civil war”.
"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," the coalition said in a statement.
Saleh had said on Wednesday he would make no more concessions to those seeking his departure.