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

Preliminary results at the end of the marathon six-week election showed his Bharatiya Janata Party (BJP) almost certain to secure the first parliamentary majority by a single party since 1984.

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 what he will deliver.

"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 him 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.

Partial figures from the Election Commission showed the BJP winning more than the 283 seats required for a majority on its own in the 543-seat parliament, 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.

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 fewer than 50 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" during the riots in Gujarat, 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 who sent messages of congratulations.

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

Modi was accused of turning a blind eye to the bloodshed shortly after he came to power. He denies the allegations and investigators have never found evidence of wrongdoing.

US Secretary of State John Kerry tweeted to say that he looked forward to working with Modi, while British Prime Minister David Cameron immediately invited him to London.

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," DK 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.

Special Correspondent from Washington adds: Ignoring the dismal human rights record of BJP's prime ministerial candidate, Narendra Modi, President Barack Obama congratulated him on his party's success in India’s ‘historic’ election, the White House said.

President Obama, who telephoned Modi, also invited him to visit Washington at a mutually agreeable time to “further strengthen our bilateral relationship,” the statement added.

The United States has denied entry visa to Modi after the 2002 massacre of Muslims in the Indian state of Gujarat when he was the chief minister.