AN advertisement used by Heathrow Airport is misleading, the Advertising Standards Authority has ruled.

The ad, which claims that “direct flights to long-haul destinations will build 20 times more trade with them than indirect flights” was found to be unsubstantiated.

It is one of seven advertisements to reviewed by ASA and the only one for which complaints were upheld.

Heathrow quoted from the One Hub or None and Frontier Economics reports, which stated: "UK business trades 20 times as much with countries where there are daily flights than with those with less frequent or no direct service.”

The ASA remained unconvinced.

John Stewart, chair of campaign group HACAN, said: “There is no excuse for a company the size of Heathrow to mislead in this way.”

“Let’s argue the case for and against a third runway on the facts.”

The news follows Tuesday’s final consultation on proposed expansion, which drew support from campaign group Back Heathrow and opposition from the Brockley Noise Action Group.

Recommendations will be made to the Government this summer.