Three ads for BT have been banned for making misleading claims about the quality of its Infinity broadband in comparison with Virgin Media and Sky.
The television ads, which screened in October, claimed that BT Infinity had more responsive online gaming and smoother video than Virgin Media and faster download speeds than Sky.
The first featured a man catching flies with chopsticks while an actress said: "Check out this guy - he's super responsive.
"But, he's not a patch on BT Infinity's super responsiveness when you're online gaming," before a voiceover added: "BT Infinity fibre optic broadband offers more responsive gaming than Virgin Media."
The second ad claimed that BT Infinity fibre optic broadband offered smoother video calling than Virgin Media, while the third said it offered faster download speeds than Sky.
One complainant, who had used Virgin Media and BT Infinity and reported no difference in their user experience, challenged whether the claims were misleading and could be substantiated, while Sky UK also complained that the comparisons were misleading.
BT defended the ads, saying independent testing by the broadband availability service SamKnows and additional tests on speeds showed that BT was the best or unbeatable on all core network metrics in relation to online gaming and for data for fixed-line broadband speeds.
The Advertising Standards Authority (ASA) said viewers would interpret the claims to meant that user experience of online gaming would be more responsive and video calling smoother with BT Infinity services than with Virgin Media services, and in relation to wireless performance as well as fixed line.
However, it found that the claims had not been adequately substantiated by the test results submitted by BT and therefore concluded that the first two ads were misleading.
It also found BT's claim that Infinity offered faster download speeds than Sky had not been adequately substantiated and was therefore misleading.
The ASA ruled that the ads must not appear again in the form complained about.
It added: "We told BT not to repeat the claims in the ads unless they held documentary evidence to substantiate them and made available sufficient information about their methodology and data for verification."
BT said: "BT notes the rulings of the ASA on these ads.
"We believed these claims were fair based on tests carried out by SamKnows and other supporting evidence we offered."