Arsenal’s Champions League final defeat by Paris Saint-Germain attracted more than 16.2 million views on illegal streams in the UK after not being made free to air.

Analysis conducted for the Guardian by the technology analyst Gaming Compliance International (GCI) shows there were 16.2m illegal stream views of longer than 90 seconds, traced to 3.7m unique IP addresses. The final was watched legally on TNT Sports and HBO Max by more than 7 million people.

TNT sparked a political row with its controversial decision not to make the final available free to air for the first time since the tournament’s rebrand as the Champions League in 1992, with Sir Keir Starmer writing to the broadcaster urging it to reconsider.

TNT is understood to have been happy with its combined linear and streaming viewing figures of more than 7m and 25.6% audience share, but the large numbers who watched illegally will be a major long‑term concern for it and all broadcasters, as well as for TV rights owners such as Uefa and the Premier League.

The absence of free-to-air coverage appears to have been a factor in the large numbers watching illegally. The 2022 Champions League final between Liverpool and Real Madrid, which BT Sport streamed for free on YouTube, attracted a peak audience of 12.6m.

The exact size of the illegal audience is impossible to discern because there is likely to have been more than one viewer for many of the 3.7m unique streams, and some viewers will have accessed more than one stream owing to technological problems and forced refreshing because of advertising, which explains the 16.2m figure.

There is a large overlap between the piracy of premium sports rights and unlicensed gambling, highlighted by the fact that 89% of adverts on illegal streams of the Champions League final were for gambling brands not licensed in the UK.

“A dark nexus has existed between illegal streaming and unregulated gambling since the pandemic, when unregulated gambling approached illegal streaming to create fake sports and gambling events to make up for the lack of professional sports at that time,” GCI’s president, Ismail Vali, said.

“Now, as markets shift with changing sports rights and rising costs for consumers, illegal streaming has become part of a new arms race for illegal gambling. They are using ‘free sports streaming’ as a unique selling point in their war against regulated gambling operators.”

TNT stood its ground and made the final available only on the subscription channels TNT Sports and HBO Max, although monthly packages for the latter start at £4.99. Industry sources said the audience there would have been higher had Uefa not brought forward the kick-off from 9pm in Budapest to 6pm, to make life easier for match-going fans.

TNT’s viewing figures for the final rose from about 4.5m for PSG’s 5-0 thrashing of Inter last year owing to the presence of an English club but declined in France because of the earlier kick-off time.

TNT disclosed that more than 9.2m people watched at least one of the three Uefa men’s finals, with 3.5m watching Aston Villa’s Europa League win and 2.7m viewing Crystal Palace’s Conference League triumph. Its average audience for European football was up 5% from last season.

Starmer, an Arsenal fan, made a second public plea for the Champions League final to be made available for free in a joint statement with the Football Supporters’ Association.

TNT had made the past two Champions League finals available for free on discovery+, and the previous rights holder BT Sport streamed them for free on YouTube.

Before BT Sport bought the rights, Champions League finals had been live on ITV, which had exclusive rights from the competition’s launch, as the rebranded European Cup, until 2003, then joint rights with Sky Sports until 2015.