KATHMANDU, August 15, 2008 (AFP) - Lawmakers in Nepal on Friday voted in former rebel Maoist leader Prachanda as the Himalayan country's first republican prime minister, officials said.

The vote in Nepal's constitutional assembly ends months of political deadlock that followed the sacking of unpopular king Gyanendra and the abolition of the 240-year-old monarchy.

It also clears the way for the ultra-leftists -- still listed by the United States as a terrorist organisation -- to press ahead with their vow to radically reform one of the world's poorest nations that was devastated by a decade of civil war.

Prachanda was backed by 464 deputies, with 113 against, constitutional assembly chairman Subash Nemwang announced.

His only rival was Sher Bahadur Deuba, a three-time former premier and member of the centrist Nepali Congress party.

Assembly members cheered, clapped and banged their desks after the results were announced.

'I am very happy and very emotional,' a visibly overwhelmed Prachanda told reporters as he left the assembly.

The charismatic former warlord had dozens of orange garlands and silk scarves offered by supporters around his neck, and his forehead was entirely covered in red powder from traditional blessings.

Prachanda, 53, led a decade-long insurgency to overthrow the monarchy -- a war which cost at least 13,000 lives and shattered the landlocked country's mainly-agricultural, subsistence-based economy.

He signed a peace deal with mainstream parties in 2006, vowed to renounce violence and steered his party to victory in elections to a new constitutional assembly in April.

Maoist number-two, Baburam Bhattarai, hailed a 'golden dawn' for Nepal.

'We have already finished destroying the roots of feudalism in Nepal, the monarchy. Under the leadership of Prachanda, the main agenda of the new administration will be nationalism, republicanism, economic and social transformation,' he said.

Born into a high-caste but poor farming family, Prachanda -- whose real name is Pushpa Kamal Dahal but chose a nom-de-guerre meaning 'the fierce one' -- was driven to politics by the extreme poverty he witnessed in rural Nepal.

But the school-teacher-turned-revolutionary, who was inspired by Chairman Mao and Peru's Shining Path, has had trouble shaking off his ruthless image.

Critics say the ultra-leftists have yet to fully abandon violence and that their feared youth wing -- the Young Communist League -- must disband to prove they are committed to peaceful democracy.

The defeated candidate congratulated the Maoists but warned the ex-rebels that they would not be allowed to install a dictatorship.

'I would like to congratulate the Maoists for entering multi-party competitive politics,' Deuba said.

'We will stay in opposition and keep an eye on the Maoists' activities while they run the government. We will oppose their actions if their activities incline towards autocracy.'