MUMBAI (Reuters) - Blackstone chief executive Stephen Schwarzman on Wednesday backed U.S. President Donald Trump's tariffs, saying they will boost manufacturing activity in the United States and spur growth in the world's largest economy.

Trump's focus on tariffs since taking office in January has rattled investors, consumers and business confidence across the globe and economists have warned about concerns of a U.S. recession and a drag on the global economy.

Schwarzman, speaking to reporters in Mumbai at Blackstone's 20th anniversary in India event, said he expects India-U.S. tariff negotiations to go relatively well in comparison to other countries following a recent meeting between Prime Minister Narendra Modi and Trump.

U.S. tariffs, he said, "will result at the end of the day in a significant increase in manufacturing activity in the United States."

"Given the size of the U.S., that tends to be a good thing for the world," Schwarzman said.

Trump has imposed a 25% tariff on imports of steel and aluminum into the U.S. and is planning similar measures for various goods.

The private equity giant also plans to double its assets under management in India in the next few years from more than $50 billion currently, Amit Dixit, head of Asia private equity at Blackstone, said on the sidelines of the event.

The U.S investment firm counts India among its top markets, and is also one of the largest owners of office buildings, shopping malls and logistics parks. It has built one of the top three hospital chains in the country and has also invested in IT services and electric vehicle components companies.

The U.S-based firm, with around $60 billion of infrastructure assets globally, will also look to deploy funds in India's infrastructure space like data centers, telecom towers, renewable energy and airports and ports, Dixit said.

"India needs infrastructure and this is something as an objective we'd like to do," Schwarzman said.