The first phase of a trade deal between India and the United States has been finalised and is undergoing legal drafting, India's trade secretary said on Thursday.

Trade secretary Rajesh Agrawal said negotiations with Washington were moving in the right direction, with legal work underway on the deal.

"We anticipate concluding and signing the trade deal at the earliest possible time," Agrawal said at a media briefing on trade data, adding that India was seeking preferential market access and greater tariff stability under the proposed agreement.

US Secretary of State Marco Rubio will visit India and Uzbekistan, from Oct. 17 to 22, and will meet government and business leaders to discuss energy cooperation, commercial investment and broader economies ties.

"Washington's decision to buy Russian diesel has raised hopes that India will avoid tariffs over its Russian oil purchases, but the United States could still use the threat of such duties to press New Delhi into an unequal trade deal," said Ajay Srivastava of the Global Trade Research Initiative.

US-India ties have been rocky this past year over issues including President Donald Trump's repeated claim of brokering an India-Pakistan ceasefire and a US military attack on a ship off Oman that killed three Indian seafarers.