We draws diplomats of the Yemen

Medical sources said 72 people died in the three days of clashes between government troops and tribal fighters.

President Ali Abdullah Saleh said once more that he will not resign, despite mounting protests.

So far, he refused to sign a contract for the transition that would see him to resign for a Government of national unity.

The United States reiterated its call on Mr. Saleh to resign, urging all parties to accept a cease-fire.

"We continue to support the departure of President Saleh, who consistently agreed that he should resign from power and then denies systematically on these agreements", Secretary of State Hillary Clinton said to journalists in Paris.

The Ministry of Foreign Affairs UK urged all British nationals to leave immediately the Yemen the fight against it degenerates.

He said his ability to provide consular assistance was limited, and airports and routes of Sanaa and other cities can be closed.

Airport of clashes

In his view of the trip, said US State Department there was "civil disorder in progress" in the country and large scale demonstrations in major cities.

It is the most intense violence since the beginning of the crisis in the Yemen there.

It follows the refusal of President Saleh signed a weekend compromise agreement, under which he would have resigned in return for an amnesty from prosecution.

Since then, opposition forces have attacked government buildings. Mr. Saleh has focused its attacks on the forces of a Chief tribal key, Sheikh Sadiq al-Ahmar.

President Saleh warned that the country could be descending into civil war. The fear of opposition it is exactly what he seeks to provoke in order to maintain his hold on power.

During this time international mediation is stalled. Neighbouring Arabic of Yemen suspended their efforts after failing to seal an agreement last weekend.

Hunters of a powerful tribal group, the Rashid, are supposed to have taken control of several public buildings in the capital Sanaa after several days of fighting Government troops.

Sana'a airport was temporarily closed on Wednesday as combatants tribes faced the Government forces.

"The State Department ordered all eligible family members of non-emergency employees of the U.S. Government and certain staff to depart from the Yemen." Citizens currently in the Yemen we should leave while commercial transportation is available. ?

UK Foreign Office advises against all travel to the Yemen since April, urging British nationals to leave the country.

Warning of the civil war

Hundreds of people were fleeing the violence in the capital, where fighting continued Thursday.

"There still sporadic artillery hits and shot in Sanaa," said Jeb Boone, Chief Editor of the Times Yemen.

"We do not know if the tribes are forcing their way in the city or if the Government forces are pushing off", he told the BBC.

Continue reading of history main Sheikh Sadiq al-Ahmar is the leader in global Rashid tribal Confederation, one of the main groups of tribal YemenHis Abdullah bin Hussein al-Ahmar - deceased father in 2007 - based brother Hamid al-Ahmar of the Islamist Islah opposition partySheikh Sadiq is a prominent businessman and member of Islah; He has repeatedly called for the resignation of Mr. Saleh another brother, Sheikh Hussein Bin Abdullah al-Ahmar, resigned the President Council governing popular in February on the shooting of President Saleh protestersLike, the Ahmars are the Zaidi Shi'a Islam branchWhile most Yemenis are Sunni Shaf'istsThe clashes began Monday after the relocation of forces loyal to President Saleh against the compound of Rachid leader Sheikh Sadiq al-Ahmar.

Medical sources told the BBC that 54 people - including Ahmar supporters, women and children - have died in fierce fighting, and 18 Government soldiers.

More than 250 people have been wounded.

The defence of the Yemen Ministry said 28 people were killed when a factory of ammunition belonging to the tribe Ahmar exploded.

While Mr. Saleh has ordered the arrest of "rebel" Mr. Ahmar and nine of his brothers, the leader of Rachid said that it was "position of strength" and ready to fight "until the end."

In an interview with defiant with Arab Network al-Jazeera Thursday, he called on several occasions Mr. Saleh a liar, accusing him of fomenting a civil war and call repeatedly for him to resign.

Mr. Ahmar said he was protected by soldiers of the army, and members of his tribe and took 70 soldiers who had surrendered as prisoners.

The BBC, Jon Leyne, said demonstrators want the President to leave immediately

He added: "I am ready to put an end to this war if Ali Abdullah Saleh too."

Mr. Saleh has so far refused to withdraw, despite international pressure intensified, warning that the Yemen could descend into civil war.

In a statement Wednesday it was ready to sign a contract of transition "in a national dialogue and a clear mechanism".

The deal Mr. Saleh has so far refused to sign, which was presented by the Gulf Cooperation Council, calls for him to resign in a month after 33 years in Office and power to a Government of national unity.