Six universities have been forced to scrap their marketing campaigns as the UK advertising watchdog launches a crackdown on misleading students with false claims.

The Advertising Standards Authority examined a range of claims – including the University of Leicester stating that it is in the “top 1%” in the world – and found that none of them could prove the assertions to be true.

Claims include Falmouth University saying it is the UK’s “number one arts and creative university”; Teesside University saying it is the “top university in England for long-term graduate prospects”; the University of Strathclyde claiming its physics department has been ranked as “number one in the UK”; the University of East Anglia’s saying it is in the “top five for student satisfaction”; and the University of West London claiming it had been named as “London’s top modern university – and one of the top 10 in the UK”.

The ASA said that the universities’ tactics broke the UK advertising code. It banned them from making the claims and assertions in the future.

The ASA has launched the crackdown to address “increasing concerns” about the way universities entice students, after the issue was thrust into the spotlight in June, when the University of Reading was forced to withdraw its claim it was in the top 1% of institutions globally.

“Our rulings send a clear message to UK universities,” said Guy Parker, the chief executive of the ASA. “If you’re making claims about your national or global ranking, student satisfaction or graduate prospects, make sure you practice what you teach: play by the advertising rules, in particular by backing up your claims with good evidence.”

The watchdog said that it felt so strongly about the issue of potentially misleading students – who are facing leaving university with huge loans that many will struggle to repay – that it is issuing new guidance to universities to make sure they abide by UK ad laws.

“Going to university involves a big financial commitment and misleading would-be students is not only unfair, it can also lead them to make choices that aren’t right for them,” said Parker. “As well as sending this message, we’re also issuing new guidance to help universities get their ads right so students can be confident they’ll get what they pay for.”

Nick Hillman, the director of the Higher Education Policy Institute thinktank, warned that universities needed to take care with their claims in a climate of growing competition to attract students.

“In the old days the top-tier universities filled up first and the other ones filled up afterwards,” he said. “But as there was a shortage of places, every university could be pretty certain of filling up. Now, with no student number controls at either an institutional or sector level, the competition for places has a touch of the wild west about it. Universities should be careful about their claims, which need to be robust, truthful and useful.”