WASHINGTON (AFP) - US Secretary of State John Kerry congratulated India's future prime minister Narendra Modi Friday after he led his Hindu nationalist Bharatiya Janata Party to a landslide election victory.

"Congrats to @ narendramodi and BJP," Kerry tweeted. "Look forward to working w/you/growing shared prosperity/security w/world's largest democracy."

Preliminary results at the end of the country's marathon six-week election showed the BJP on track for the first parliamentary majority by a single party since 1984.

In a victory speech, Modi - an abrasive former tea boy - promised to fulfill the dreams of all Indians.

"The heat of the election is over and the people have given their verdict, which says that we need to take India forward to fulfil the dreams of India's 1.2 billion people," he said at a rally in Gujarat.

The BJP's win - which exceeded all forecasts - 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.

On Monday, US President Barack Obama pledged to work closely with the next government in New Dehli - but did not mention the BJP or Modi.

The United States had for years refused to deal with Modi over allegations he failed to swiftly curb deadly 2002 anti-Muslim riots in Gujarat that left at least 1,000 people dead shortly after he came to power as chief minister there.

Washington ended its boycott of Modi in February when Nancy Powell, the outgoing US ambassador to India, shook hands with him at the start of closed-door talks.

In 2005, the United States refused Modi a visa under a domestic law that bars entry to any foreign official seen as responsible for severe violations of religious freedom.