Sushil Koirala, Nepal's new prime minister charged with steering the strife-torn country towards stability, is well versed in the rough and tumble of his country's politics, having spent three years in jail for helping to hijack a plane.

Koirala, 75, is president of the country's oldest party, the Nepali Congress, which has long been controlled by his family. Three of his relatives have been prime minister in the past.

When he was in his 30s and exiled with his family in India, Koirala was involved in hijacking a plane, known to be carrying boxes of cash, which he and his relatives wanted to use to fund their Nepali Congress party.

At the time, Nepal was run under a party-less "panchayat" system overseen by a monarchy that had overthrown a shortlived democratically elected government in 1960.

A veteran politician and activist, Koirala won a majority vote on Monday in the new parliament to become prime minister, ending months of deadlock over who would lead the nation following elections last year.

The unmarried, bearded leader has the tough task of guiding the new constituent assembly, or parliament, as it writes a constitution that can deliver stability to Nepal eight years after the end of a civil war.

The peace process saw the Hindu kingdom transformed into a secular republic. But Nepal has been in political limbo for nearly two years, since the dissolution of the country's first constituent assembly.

In an interview last December, Sushil Koirala underlined the urgency of building consensus, telling The Kathmandu Post newspaper, "our responsibility is to accommodate everyone".

"If we get into another conflict, we will lose all dignity and Nepal will be seen as an international failure."

Koirala, usually pictured in his trademark black cap and glasses, has pledged to draft the constitution within 12 months, after a series of short-lived coalition governments failed to do so following Nepal's first post-war elections in 2008.

Links to India

Koirala was born in 1939 in eastern Nepal, but his family fled to India in 1960 after the then king suspended democracy and jailed dozens, including some of his relatives, one of whom was prime minister.

He registered for a degree in humanities at a university in the ancient Indian town of Varanasi, but it was his exposure to an older relative, G.P. Koirala, that would eventually shape his future.

Exiled to India after spending seven years in prison, G.P. Koirala masterminded the plan to hijack a Royal Nepal Airlines plane, known to be carrying hundreds of thousands of dollars in cash from a state-owned bank.

Hijackers forced the pilot of the Kathmandu-bound plane to land in eastern India instead, where a team of five, including Sushil Koirala, lay in wait, ready to grab the cargo.

Within a year, Indian authorities had arrested most of the activists involved in the ambush and Koirala spent three years in jail.

After his release, he owed his assent to G.P. Koirala, who returned to Nepal after an amnesty by the king and became prime minister in 1991 following mass pro-democracy protests.

Two years before his death, G.P. Koirala appointed his younger relative acting president of the Nepali Congress in 2008.

"G.P. Koirala's blessing made it possible for Sushil to rise so far, because the Koiralas don't want non-family outsiders to become too powerful in the party," Lok Raj Baral, executive chairman of Kathmandu's Nepal Centre for Contemporary Studies, told AFP.

"Sushil Koirala's main assets are an accident of birth, a clean reputation and total loyalty to the Koirala clan," Baral said.