It is a scene familiar from many a TV advert for lager: a group of laughing young men walk down the pavement for an evening pint in their local pub. But this time, rather than being dressed in casual shirts they're kitted out in bright, building site-style fluorescent jackets.

That, at least, is the vision outlined by campaigners currently engaged in a row with the Advertising Standards Authority, the watchdog which some critics allege has recently begun to overextend its remit into highly contentious areas of road safety.

The spat began on Wednesday when the ASA upheld complaints about a TV advert from Cycling Scotland shown as part of a cycle safety campaign. The ASA ruled the ad should be banned on public safety grounds as it portrayed a cyclist without a helmet and riding too far from the kerb.

An aghast Cycling Scotland pointed out that cycle helmets are not compulsory, and that police and the highway code specifically advise cyclists that it is safest to position themselves some way into their lane. The ASA conceded a likely error over the latter point and withdrew its ruling pending an independent review. However, it appeared to stay firm over the helmet, which it argues should be shown in advertisements as their use, while not compelled under law, is recommended by the highway code.

This has worried cycle campaigners, who point out that the extent of safety benefits from helmets is contested, while an insistence on their portrayal wrongly portrays cycling as an inherently dangerous pursuit needing specialist equipment, rather than an everyday activity.

The CTC, a national cycling campaign group, has now hatched a plan to bombard the ASA with complaints about advertisements which breach other advice in the highway code, notably the little known and very rarely adhered to rule for pedestrians which advises those on foot after dark – whether on pavements or not – to wear reflective gear like armbands, waistcoats or jackets.

The CTC has appealed to the public for examples, and these have duly begun to arrive. Among seeming infractions tweeted to the CTC include one advertisement for a car sales website which features a black-clad pedestrian on a pavement at night, and a Christmas ad for the retailer Boots which features a young man in a hooded top – without a reflective strip in sight – chasing round his dark, snowy neighbourhood to deliver last-minute presents.

Such examples were deliberately absurd, said Roger Geffen, policy director for the CTC: "This is the point: our concern is that the ASA used the highway code as a reason to back down on the bit of their ruling about road positioning but also used it to stick to their guns on the helmet. That's why we've got to say, there's quite a lot of rules in the highway code that are not part of normal life and shouldn't be the basis for effectively imposing censorship on anyone not complying.

"You're less likely to be killed in a mile of cycling compared with a mile of walking. That's why we've got this concern about the creeping compulsion thing. We've got to present cycling as a perfectly normal thing people can do in whatever clothes they would normally be wearing."

An ASA spokesman said the body could not speculate on whether adverts showing pedestrians at night in everyday clothes would also breach rules. He said: "It's not something that we can look at in advance. If any complaints are made we will look at them then, though not every complaint will result in an investigation.

"It's about the merits and context of an individual ad, rather than a broad sweep. But that obviously is for the complaints and investigations staff to assess."