India-US ties have grown significantly over the past year, with Washington emerging as an important energy supplier to New Delhi as it diversifies its sources, a senior US official has said.

US Department of State Deputy Assistant Secretary Bethany Morrison on Thursday said the relationship between the two countries now spans energy, defence, commercial cooperation and multilateral engagements, with South Asia becoming a major priority for the Trump administration.

"When you look at India, just over the last year with the US-India partnership, the scale and breadth of that relationship has grown from last year," Morrison said at a roundtable organised at the New York Foreign Press Centre.

She also cited the 10-year defence framework agreement between India and the US and new initiatives in the energy sector as examples of the expanding partnership.

"India for the first time in 20 years reformed their nuclear regulatory environment by passing the SHANTI Act, and now we're moving forward on some really exciting developments in civil nuclear cooperation," Morrison said.

"We're now very proudly the largest exporter of LPG to India, so when we talk about diversifying energy sources, we are happy that the United States is now becoming that provider," she added.

Morrison said cooperation ranged from energy and major commercial deals to defence engagements and multilateral diplomatic meetings such as the Quad.

She said the broader South Asian region had become a major priority for the Trump administration.

"We're very, very excited about that. It's often a region that historically gets overlooked until there's a crisis because of all everything else happening in the world, from what's happening in Latin America to Africa to the Middle East, and then obviously land wars in Europe," she said.

"But really, we see South Asia as such a critical sort of part of the world that really has not gotten enough attention, and that's where President Trump has really made sure that he has advised us to do," Morrison said.