Triumphant Hindu nationalist Narendra Modi pledged to make it "India's century" as he propelled his right-wing party to a stunning electoral triumph Friday with the biggest winning margin for 30 years.

Final results at the end of the six-week election showed his Bharatiya Janata Party (BJP) had secured the first parliamentary majority by a single party since 1984 on a platform of economic growth and clean government.

Most of the poverty-wracked country's 1.2 billion people -- more than half of whom are under 25 -- have never witnessed such dominance having grown up in an era of fractious coalition politics.

Modi, an abrasive former tea boy tainted by anti-Muslim riots in his home state of Gujarat in 2002, promised to work for all Indians and particularly the young as he fed building expectations of new jobs and development.

"I want to make the 21st century India's century. It will take 10 years, not very long," said the four-term chief minister of western Gujarat who is expected to be sworn in as prime minister next week.

Speaking to cheering supporters who chanted his name and let off fireworks, he also made clear efforts to sound inclusive amid deep suspicion of the hardliner among religious minorities, particularly Muslims.

"I want to take all of you with me to take this country forward... it is my responsibility to take all of you with me to run this country," Modi added in front of a crowd of thousands in his constituency of Vadodara.

The results exceeded all forecasts. Petals were showered outside BJP offices around the country, sweets were handed out to celebrate and painted elephants paraded in front of party headquarters in New Delhi.

The BJP's triumph redraws India's political map, elevating the party to a pan-national power, handing Modi a huge mandate for change, and heaping humiliation on the ruling Gandhi political dynasty.

Modi, 63, will face pressure to deliver a quick improvement in the economy, growing at its slowest rate in a decade, amid anxiety about the BJP's Hindu nationalist agenda which could stir religious tensions.

Official figures from the Election Commission showed the BJP had secured 275 seats and was projected to win another seven, with victories by its allies taking it easily in excess of 330.

"It is the dawn of a new era. The lotus has bloomed all over India now," said BJP president Rajnath Singh, referring to the flower symbol of his party, whose previous all-time high was 182 seats in 1999.

- 'No magic wand' -

The Congress party, the national secular force that has run India for all but 13 years since independence, was set to crash to its worst ever result with 44 seats, less than a quarter of its tally in 2009.

It has headed two successive left-leaning coalition governments since 2004.

The disastrous showing is a severe blow to the Gandhi dynasty which runs Congress, particularly for 43-year-old scion Rahul, whose first performance as chief national campaigner will lead to acrimonious fallout.

Smiling despite the grim news, Rahul admitted in brief remarks that Congress had "done pretty badly".

"As vice-president of the party I hold myself responsible," he said.

Outgoing Prime Minister Manmohan Singh, who said in January that Modi would be "disastrous for the country" after "presiding over the massacre of innocents", called to congratulate the BJP leader.

While Singh, 81, was hailed by US President Barack Obama as a "wise and decent man", Modi presents an awkward prospect for Washington and other Western powers.

The strict vegetarian, elected three times as chief minister in his home state, was boycotted by the US and Europe over 2002 riots in Gujarat that left around 1,000 people, mostly Muslims, dead.

He was accused of turning a blind eye to the bloodshed shortly after he came to power, but he has always denied the allegations. Investigators have never found evidence of wrongdoing.

US President Barack Obama on Friday telephoned Modi and called for a "strong partnership", an aide said, while the White House said a former visa ban targeting him would be overturned.

British Prime Minister David Cameron rang to invite him to London, while Pakistani premier Nawaz Sharif hailed an "impressive victory".

- Heady optimism -

On financial markets, India's main Bombay Stock Exchange index closed up 0.9 percent after surging to a record high earlier in the day.

Investors and the wider public have rediscovered heady -- many say unrealistic -- optimism about the world's second-most populous nation after years of frustration about weak leadership, rising food prices and corruption.

"The economic problems are quite acute. There's no magic wand," D.K. Joshi, chief economist of credit rating agency Crisil, told AFP.

India is in the grip of stagflation -- growth has slumped to 4.9 percent from nine percent two years ago, and consumer inflation is at a wage-eroding 8.6 percent.

Modi has reinvented himself from a controversial regional leader whose career was nearly ended by the 2002 riots to a statesman intent on helping India industrialise and create jobs.

His promises to revive the economy have won him corporate cheerleaders, while his rags-to-riches story and reputation as a clean and efficient administrator satisfy many Indians' desire for strong leadership.