Complaints about advertising reached a record level last year, according to the industry's watchdog.

In an interview with ePolitix.com, Lord Borrie QC, the head of the Advertising Standards Authority, said complaints about direct mail were causing particular concern.

Last year saw more than 12,500 complaints to the watchdog: with a 51 per cent rise in members of the public being offended by mailshots.

The biggest number of complaints were generated from a mailshot for the slimming pill Berry Trim Plus, sent by Health Laboratories of North America.

"This had a handwritten message at the top, with the recipient's initials and the words 'Try it, it works'. This deception - implying that the mailing was from a friend or relative - caused particular distress, and was a flagrant breach of the code," he said.

"That was one of the most worrying ads that we upheld complaints about last year."

Advertisers using new technology has led to new abuses of advertising rules.

The watchdog has recorded a 50 per cent rise in complaints regarding internet advertising.

For the first time the ASA upheld a complaint about an advert sent as a text message to mobile phones.

Lord Borrie rejected claims that the industry is too big to be effectively regulated.

"Potentially it could be because of the speed at which ads change, but we do have some experience of being able to act urgently on a fast track basis," he said.

"We certainly do this with posters - our recent adjudication against the ad for the Ali G film meant that we ruled within a week of the posters first appearing and they were removed straight away."

"We can act very speedily and we've got procedures in place to enable the part-time members of our council to adjudicate by telephone if that is required urgently, whether it's a poster or whether it's something on the internet."

In the ASA's annual report, which is published today, he warned the advertising industry that its freedom was conditional on maintaining standards of decency and taste.

"If advertisers, or agencies, feel inclined to excuse themselves from a breach of the Codes on the grounds that 'only one person complained', I would urge them to think again," he said.

"It is the responsibility of the industry to exercise self-restraint in order to secure advertising freedom in the future."