LONDON, June 11 (Reuters) - Some of the world's biggest carmakers are facing 1.5 million lawsuits in Britain for allegedly cheating emissions tests that could cost them at least 6 billion pounds ($7.6 billion), claimants' lawyers told London's High Court on Tuesday.

The claims, brought by owners of diesel vehicles, highlight the ongoing fallout for automakers from a scandal that erupted in 2015 when Volkswagen admitted to using "defeat devices" to change diesel vehicles' emissions levels during testing.

Manufacturers including Mercedes-Benz and Ford are also alleged to have misled customers about certain vehicles' compliance with nitrogen oxide emissions standards – which the companies deny.

A spokesperson for Mercedes-Benz – which faces around 300,000 claims – said in a statement: "We continue to believe that the claims against Mercedes-Benz are without merit and will vigorously defend ourselves against them or any group action with the necessary legal means."

A Ford spokesperson said: "We see no merit in these claims and are robustly defending against them. Our vehicles and engines meet all applicable emissions requirements."

Volkswagen's "dieselgate" scandal has cost the carmaker more than 32 billion euros ($34 billion) in vehicle refits, fines and legal costs.

The German group agreed to pay 193 million pounds in 2022 to settle claims from around 91,000 British drivers without any admission of liability.

Lawyers representing a coalition of claimants said at a preliminary hearing that there were around 1.5 million claimants suing 13 different vehicle manufacturing groups.

Benjamin Williams, one of the claimants' lawyers, said in court documents that the value of individual claims had not yet been determined.

But he said that "even if the claims were valued conservatively" at 4,000 pounds each, it would make the total value of all of the lawsuits "at least" 6 billion pounds.

The legal costs of the litigation will also be huge, with the claimants' lawyers estimating they will need to spend nearly 400 million pounds up to a potential third trial in 2026, with the carmakers' figure being 321 million pounds. (Reporting by Sam Tobin; Editing by Mark Potter)