United Kingdom Prime Minister Keir Starmer is to visit India "at the earliest opportunity" following the agreement of a free-trade deal between the two countries that has been hailed as a historic moment for both nations.

Preparatory work on the deal, which will slash tariffs on exports of UK goods including whisky, cosmetics, and cars and also see 99 percent of Indian exports including food, spices, and textiles become free from import duties, was begun three years ago under a previous UK government.

Starmer said it was "the biggest trade deal that we the UK have done since we left the (European Union), and it's the most ambitious trade deal that India has ever done". His Indian counterpart, Narendra Modi, described the agreement as "ambitious and mutually beneficial".

The UK expects the deal to boost bilateral trade by 25.5 billion pounds ($34 billion) a year from 2040, adding nearly 5 billion pounds to the economy each year, while a representative from Modi's office said it would also "unlock new potential for the two nations to jointly develop products and services for global markets".

India and the UK, the world's fifth- and sixth-largest economies respectively, already have long-standing and close cultural ties dating back to the colonial era, and the securing of such a substantial agreement is a major landmark for both countries at a time when tariffs have caused so much global economic and trading instability.

With its population of 1.4 billion people, India is the world's largest market for whisky, and Mark Kent, chief executive of the Scotch Whisky Association, said the deal would be "transformational", with "the potential to increase Scotch whisky exports to India by 1 billion pounds over the next five years".

One of the things that proved problematic in the discussions was the topic of UK visas for Indian nationals, with immigration having been a major issue in last summer's UK general election and also in recent local elections that saw the anti-immigration Reform Party enjoy significant success.

Business Secretary Jonathan Reynolds said the deal had made "modest changes to business mobility", with new groups of workers from India, including chefs, being added to those who can apply for UK visas.

India's National Association of Software and Service Companies was particularly enthusiastic about a part of the deal that sees skilled Indian workers in the UK and their employers exempted from having to pay social security contributions for three years, saying this would boost employment access and create work opportunities.

"The provision reflects the recognition of India's strength in delivering high-quality services globally and reinforces the importance of mobility for Indian professionals in driving innovation and growth", it added.