KATHMANDU (AFP) - Nepal's parliament on Sunday chose veteran politician K P Sharma Oli as the new prime minister, weeks after the quake-devastated country adopted a new constitution, the speaker announced.

Mr Oli won 338 votes in a parliamentary ballot, defeating rival candidate Sushil Koirala who took 249, after he stepped down as premier as required by the constitution adopted on September 24.

"I announce that respected member KP Sharma Oli has been elected to the post of Nepal's prime minister," speaker Subash Chandra Nembang told the parliament to loud cheers.

Mr Oli of the Communist Party of Nepal (Unified Marxist Leninist) has vowed to speed up rebuilding after an earthquake hit the impoverished nation in April and claimed nearly 8,900 lives.

"Our country has been devastated by the earthquake. I will accelerate the reconstruction process," he told lawmakers ahead of the vote.

The 63-year-old will also have to quell continuing protests over the new constitution and end a blockade which has led to nationwide fuel rationing.

The constitution is aimed at bolstering the Himalayan country's transformation to a peaceful democracy after decades of political instability and a civil war.

But protesters from Nepal's southern plains are incensed about the charter, which will divide the country into several federal provinces.

During his speech before the ballot, Mr Koirala vowed to work with Mr Oli if he was defeated on Sunday, for the good of the country.