SANAA (AFP) – Tanks were deployed outside the presidential palace in Yemen on Monday, as a top general announced his allegiance to the protest movement seeking to oust President Ali Abdallah Saleh from power.

Tanks took up positions in key locations across Sanaa including at the presidential palace, the central bank and the ministry of defence, an AFP correspondent saw.

The deployment came as General Ali Mohsen al-Ahmar, an armoured infantry division commander, announced that he had joined the "revolution" along with other senior officers.

"The crisis is getting more complicated and it's pushing the country towards violence and civil war," he said in a statement broadcast by Al-Jazeera television.

"According to what I'm feeling, and according to the feelings of my partner commanders and soldiers... I announce our support and our peaceful backing to the youth revolution.

"We are going to fulfil our duties in preserving security and stability."

Ahmar is the most senior military officer to pledge support for the opposition, which has been agitating for weeks to end Saleh's 32-year rule over the impoverished, tribal country.

His pledge comes a day after Saleh sacked his cabinet in a bid to placate opposition calls for sweeping reforms.

The regime has already been weakened by the resignations of ministers, ambassadors and a host of ruling party MPs, but Saleh has refused to stand down until his term ends in 2013.

His regime was internationally condemned after more than 50 people were killed as loyalist gunmen opened fire on protesters in Sanaa's University Square, the centre of the pro-democracy movement.

The defection of top military officers to the opposition is likely to complicate Washington's support for Saleh, whom it sees as a pillar of stability in a volatile country and a partner in the war against Al-Qaeda.

There were unconfirmed reports that other generals and several ambassadors had also pledged their support to the "revolution," in what could be the endgame of a long and bloody period of unrest in the strategic Arab state.

The country's ambassador to the UN and human rights minister resigned on Sunday in protest at the brutal treatment of peaceful protesters.

Politicians and civil society leaders joined in a massive funeral procession in Sanaa on Sunday for some of those killed last week, in what amounted to one of the biggest anti-regime demonstrations since the protests began late January.

UN Secretary General Ban Ki-moon on Monday strongly condemned the use of live ammunition against demonstrators in Yemen, and repeated international calls for dialogue and restraint.

"The Yemen government has an obligation to protect civilians. I call for the utmost retraint and end to violence," Ban told reporters following talks with Arab League chief Amr Mussa in Cairo.

"There is no alternative to an inclusive dialogue on political, social and economic reform to address Yemen's political crisis."