More than 40 Yemenis were killed as violence erupted in Sana’a peaceful pro-democracy protests. Yemen was on the verge of a civil war as there was overnight combat between the government forces and tribal militia.

On Thursday, residents were seen abandoning the city in thousands to escape violence as the protests entered fourth day while clashes erupted after President Ali Abdullah Saleh rejected the agreement to step down and bring an end to the four months of unrest.

The fighting, between Saleh's security and members of the Hashed tribe which was led by Sadiq al-Ahmar, was one of the bloodiest Yemen clash since the protests began in January.

Leaders of the Group of Eight (G8) summit meeting in France also called on Saleh to quit.

We deplore the fighting that occurred overnight which was a direct result of the current political impasse, for which President Saleh has direct responsibility due to his refusal to sign the GCC transition agreement, a French Foreign Ministry spokesman said, referring to the Gulf Cooperation Council, reported Reuters.

The United States, which for long treated Saleh as an ally against al Qaeda, said it now wanted him to go.

U.S. Secretary of State Hillary Clinton said he had consistently reneged on agreements to step down.

Tribal leader Ahmar told Reuters there was no chance for mediation with Saleh and he called on regional and global powers to force him out before the country of 23 million people plunges into civil war.

Ali Abdullah Saleh is a liar, liar, liar, said Ahmar. We are firm. He will leave this country barefoot.

However, Saleh said on Wednesday he would not agree to international diktats to step down and leave Yemen.

The pressure has been mounting since February, when protesters inspired by democratic revolutions in Egypt and Tunisia began their camping in squares and marching in their hundreds of thousands calling for Saleh to go.

Saleh’s attempts to stop the protesters by force have so far claimed the lives of more than 260 people.