LONDON (Reuters) - Athletic wear giant Adidas and fashion house Thom Browne resumed their legal battle on Wednesday, with London's High Court hearing the latest round of a global dispute focused on their competing striped trademarks.

New York designer Thom Browne, who regularly uses a four-bar stripe pattern, sued Adidas in London in 2021 to revoke several trademarks featuring Adidas' iconic three-stripe motif.

Thom Browne, which changed from a three-bar pattern in 2007 after Adidas complained, argues Adidas is effectively trying to establish a monopoly on the use of stripes on clothes.

Adidas, however, is countersuing Thom Browne for allegedly infringing its trademarks by selling leisure and sportswear featuring four stripes, accusing it of exploiting Adidas' reputation and brand image.

The two companies have previously faced off in the United States, where a jury rejected Adidas' trademark lawsuit last year, a decision upheld on appeal in May.

Thom Browne is also bringing separate trademark litigation against Adidas in the Netherlands and at the European Union Intellectual Property Office.

With its eponymous founder watching on in court, Thom Browne's lawyer Philip Roberts said that Adidas had used certain trademarks as "Trojan horses" to prevent the use of stripes on other companies' products.

Roberts added in court filings that "the breadth of Adidas' asserted monopoly threatens the basic freedom of fashion designers to design clothing in the manner they wish".

But Adidas' lawyer Charlotte May said in court filings that Thom Browne's 2020 launch of a sportswear range was a tipping point which "strikes at the heart of the Adidas business".

She pointed to a collaboration with NBA star LeBron James and a partnership with Spanish soccer team Barcelona, when Adidas-sponsored player Lionel Messi was at the club, as evidence that "Thom Browne intend to continue their encroachment into sportswear and sports marketing".

The trial is expected to conclude next week.