The trail was withdrawn ahead of schedule in December 2005

The Faces campaign - which featured a giant animated head made up of smaller heads - generated more than 1,000 complaints when it was shown in 2005.

One viewer described the trail as "disturbingly psychotic".

The board of governors added that the BBC should have apologised for causing offence when it withdrew the advert.

The governors' programme complaints committee - which operates independently of the BBC - discovered the corporation had been warned the trail would cause distress.

'Strong reaction'

According to the BBC's Editorial Policy Unit, the trail would be "predictably unsettling to sections of the audience".

"'Playing' with the human face and image typically elicits a strong reaction in these segments," it said.

The BBC's guidelines say that trails shown when children are likely to be watching should be suitable for the audience.

As the advert had been shown next to programmes such as EastEnders, Neighbours, and Strictly Come Dancing, the committee felt the BBC had broken these guidelines.

The committee also criticised the BBC's reaction to the complaints.

At the time, the corporation said it had taken the trail off air because it had achieved its purpose.

However, the governors felt the BBC should have acknowledged the role of audience complaints in the decision to withdraw the advert, and should have apologised for causing offence.

'Racist slur'

The complaints committee considers appeals from members of the public who are dissatisfied with the way the BBC has handled their complaints.

In its latest report, it considered complaints about bad language in Doctor Who and the comedy series Love Soup, neither of which were upheld.

Complaints against Doctor Who were not upheld by the governors

Nor did it uphold a complaint that Jeremy Clarkson had made a "racist slur" against Germany in an edition of Top Gear.

The committee found that the material was an example of Clarkson "using outrageous behaviour to amuse his audience".

"The remarks would not have led to anyone entertaining new or different feelings or concerns about Germans or Germany," it continued.

However, the committee did apologise on behalf of the BBC to one complainant who felt she had been unfairly treated by the topical comedy programme Late Edition.

She had been interviewed for an item about phone masts on the programme, but was led to believe the feature would be serious, rather than comedic.

The BBC's internal Editorial Complaints Unit had already apologised to the organisation Mast Sanity, which had put the woman forward for interview.