|Clashes have erupted between embattled Saleh's security forces and gunmen from Yemen's most powerful tribe [EPA]
At least 38 people have been killed in heavy fighting in the Yemeni capital between government loyalists and guards of a tribal leader who has sided with protesters demanding an end to president Ali Abdullah Saleh's rule, reports say.
Witnesses said the two sides exchanged sporadic gunfire in Sanaa on Tuesday.
The resumption of clashes after a nighttime lull dimmed prospects for a political solution to a three-month revolt inspired by protests that swept aside the leaders of Egypt and Tunisia.
"Gunmen and soldiers spread out everywhere and the sound of gunfire can be heard from time to time," one witness told the Reuters news agency.
A security official said 14 soldiers were killed in the fighting and 20 others were missing. A hospital official said 24 tribesmen were killed. Both officials spoke on condition of anonymity because of the sensitivity of the matter.
Fighting in the same area on Monday killed seven people, including a civilian bystander.
The clashes pitted government troops against guards of Sadiq al-Ahmar, head of the Hashed tribal federation.
The government accused Ahmar's men of igniting the clashes on Monday by firing on a school and the headquarters of state news agency Saba. Ahmar's office said government forces opened fire when his guards prevented them from entering a school where Ahmar said Saleh loyalists were stockpiling weapons.
Early on Tuesday, tribal mediators were holding talks to try to bring an end to the clashes, a source in Sadiq al-Ahmar's office said. Saleh is also from the Hashed federation.
Sheikh Hamid, the brother of Sadiq al-Ahmar said: "We consider this an attempt from Saleh to destabilise the revolution and change it from its peaceful course after he realised he has to leave but we assure you that the revolution will remain peaceful."
The clashes followed the collapse on Sunday of a transition deal mediated by Gulf neighbours that Saleh was to have signed that would have given him immunity from prosecution, ensuring a dignified exit.
The United States and Saudi Arabia, both targets of foiled attacks by a wing of al-Qaeda based in Yemen, are keen to end the Yemeni stalemate and avert a spread of anarchy that could give the global network more room to operate.
Saleh, playing on Western fears of chaos, blamed the opposition for the deal's collapse and warned that if a civil war erupted "they will be responsible for it and the bloodshed".
Yet Yemen rejected any interference in its internal affairs and expressed "regret" over France's criticism of Saleh's failure to ink a Gulf-brokered accord on giving up power after months of deadly anti-regime protests, the foreign ministry said on Tuesday.
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"Resolving the political crisis in Yemen is a Yemeni affair and the Republic of Yemen does not accept orders from any party ... and rejects any interference in its internal affairs," the ministry said, according to the state news agency.
"This new U-turn is irresponsible and unacceptable," Bernard Valero, a French foreign ministry spokesperson, had told reporters.
"If president Saleh persists in refusing to respect his commitments, France is ready to take up all the consequences, with the European Union and its European partners," he said, without giving details of possible measures.
The Philippines government, meanwhile, offered to fly home all its 1,400 citizens in Yemen on Tuesday as the political violence intensified.
The government also ordered a halt to the deployment of Philippine workers to Yemen but stopped short of calling for a mandatory evacuation.
The wave of unrest in the Middle East and North Africa has displaced thousands of Filipinos working there, with about 26,000 having already fled Libya.