MUMBAI (Reuters) -British Prime Minister Keir Starmer and his Indian counterpart Narendra Modi will celebrate their countries' deepening commercial ties on Thursday with an announcement of further Indian investment into the UK and a meeting between the two.

Starmer's office said he would use the second and final day of a trip to India to discuss a recently-sealed trade deal as well as a technology security initiative launched in July last year.

It also said that 64 Indian companies would collectively invest 1.3 billion pounds ($1.75 billion) in Britain, announced during a visit of the UK's largest ever trade mission to India, with more than 100 companies and organisations travelling with the prime minister.

"The UK-India trade deal is already unlocking growth, and today's announcements mark the beginning of a new era of collaboration between our two nations," Starmer said.

The deal between the world's fifth and sixth largest economies, agreed after U.S. President Donald Trump unleashed tariff turmoil, aims to increase bilateral trade by a further 25.5 billion pounds by 2040.

In a readout of a meeting of the countries' trade ministers on Wednesday, India's commerce ministry said they agreed to work more closely in sectors including advanced manufacturing, digital trade, clean energy and services.

But the countries do not agree on everything. After Modi wished Russian President Vladimir Putin happy birthday on Tuesday, Starmer joked to reporters that he would not be doing the same, given Britain's strong backing for Ukraine and condemnation of Russia over its invasion.

Britain says it respects India's strategic independence and Scottish Secretary Douglas Alexander, a former trade minister who joined the UK delegation, told reporters the issue had not prevented Starmer from leveraging a close relationship with Modi to grow the UK economy.

($1 = 0.7444 pounds)