A new horror film in which giant spiders invade an American small town has terrified arachnophobes with its poster campaign.

The lifelike posters for Eight Legged Freaks have provoked more than 50 complaints to the Advertising Standards Authority from people with a fear of spiders. One complained that he almost crashed his car when he was startled by a large roadside poster depicting one of the film's mutant spiders attacking a human.

The posters were put on display across the country before the film was released last week and some feature three-dimensional spiders beside the words, "Eight Legged Freaks ... Let the squashing begin".

It is the second controversial episode surrounding the Warner Brothers production. The film company had to drop its original title, Arac Attack, because of the possibility of an American invasion of Iraq.

A spokesman for the Advertising Standards Authority said it was the highest number of spider-related complaints the organisation had received, although arachnophiles had also complained.

"The arachnophobes think that it is distressing and object to it being on a poster. Obviously, they have a recognised phobia and some of them have said it is Britain's most common phobia. We have also had two complaints from people about the words 'let the squashing begin'. Apparently, they think that it's likely to make people kill and squash spiders," she said.

The ASA has been receiving two or three complaints a day about the posters since the start of August. Its code says that no advertisement should cause fear or distress without good reason and that advertisers should not use shocking images to attract attention. However, to investigate a complaint, a risk of the image causing "serious or widespread offence" must be evident. Last night, the spokeswoman said the ASA had decided that it could not investigate the complaints because the offence caused would not be sufficiently widespread.