Obama Says U.S. and India Can be 'Best Partners'

President Barack Obama said the United States could be India's "best partner" Tuesday as he wrapped up a three-day visit to New Delhi by highlighting the shared values of the world's biggest democracies.

Speaking to an audience of young people, the U.S. president reiterated that the relationship between Washington and New Delhi "can be one of the defining partnerships of this century" but warned the battle against climate change would be doomed unless India was fully on board.

The speech was the finale of a packed visit which has seen a dramatic upturn in an often troubled relationship, including the signing of a new "friendship" declaration between Obama and Prime Minister Narendra Modi.

The right-wing premier was persona non grata in Washington less than a year ago but has developed a close bond with Obama, with their two countries both keen to counter-balance the rise of China.

"India and the United States are not just natural partners -- I believe that America can be India's best partner," said Obama after receiving a rapturous welcome from a group of around 1,500 people.

"Of course, only Indians can decide India's role in the world. But I'm here because I am absolutely convinced that both our peoples will have more jobs and opportunity, our nations will be more secure, and the world will be a safer and more just place when our two democracies stand together."

Obama's speech was the final engagement on his visit, the centre-piece of which was his attendance as chief guest at Monday's Republic Day parade -- one of the biggest honours that India can bestow on a foreign leader.

- Personal rapport - 

Both Obama and Modi have been at pains to demonstrate their personal rapport during the visit and announced a breakthrough on a nuclear deal on Sunday that had stalled under India's last government, although there have been few other substantive policy announcements.

Obama, who hosted Modi in Washington in September, has said the "stars are aligned" to realise the ambitions he expressed when he last visited in 2010 for the two countries to become global partners.

The United States is looking to reinvigorate alliances in the Asia-Pacific as part of Obama's "pivot" east, and has taken note of Modi's more assertive stance towards China than his predecessor.

Beijing claims sovereignty over large swathes of the South China Sea, home to maritime lanes that are vital to global trade, and is engaged in territorial disputes with a host of nations in the region.

But in his speech, Obama said that freedom of navigation must be upheld.

"The United States welcomes a greater role for India in the Asia Pacific, where the freedom of navigation must be upheld and disputes must be resolved peacefully," Obama said.

Speaking after their talks on Sunday, Modi said he would not be pressured on climate by any country -- comments seen in part as aimed at China after it agreed on new carbon emissions targets with the U.S.

- Climate plea - 

But Obama warned the world does not "stand a chance against climate change" unless developing countries reduce dependence on fossil fuels.

"I know the argument made by some, that it's unfair for countries like the United States to ask developing nations and emerging economies like India to reduce your dependence on the same fossil fuels that helped power our growth for more than a century," Obama said.

"But here's the truth: even if countries like the United States curb our emissions, if growing countries like India -- with soaring energy needs -- don't also embrace cleaner fuels, then we don't stand a chance against climate change."

India has balked at committing itself to major cuts in carbon emissions ahead of a U.N. climate summit in December, arguing that it will not set itself targets that undermine efforts to boost living standards in a country where many of the 1.2 billion population live in poverty.

On Monday, Modi vowed to banish India's reputation as a tough place to do business, promising a competitive tax regime and an end to excessive red tape in a pitch to U.S. executives delivered alongside Obama.

The Indian premier extended a personal invitation to Obama, a measure of the turnaround in relations after a tense row involving the arrest and strip-search of an Indian diplomat in New York in 2013.

The bonhomie between the two leaders is all the more remarkable given that Modi was persona non grata in Washington only a year ago after deadly communal riots in Gujarat when he was state chief minister in 2002.

Obama had been due to visit the Taj Mahal with his wife Michelle Tuesday, but the trip was cut short after the death of the former Saudi king.