Parents have been advised not to dress their schoolchildren in short skirts and tight trousers amid fears they could be targeted by paedophiles.
The advice to families of children at King's Park Secondary School in Glasgow was sent out as part of new guidelines on dress codes.
Glasgow City Council confirmed the warning was linked to the recent conviction of a local paedophile.
The Scottish Parent Teacher Council said "shock tactics" were not needed.
In the letter to parents, the school states: "We believe that an appropriate school uniform (eg school trousers, knee-length school skirt etc) protects children from being targeted by sexual predators.
"There is recent evidence in the south of Glasgow of adults photographing school girls in short skirts and school girls/boys in tight trousers, then grooming them through the internet.
"We must do all we can to keep our children safe. A modest school uniform is more appropriate than fashion skirts, trousers or tops."
The letter advised parents to buy "appropriate" school uniforms from a list of approved items at Marks and Spencer.
A council spokeswoman said the choice of store was an advisory only, and was not intended as an advertisement for M&S.
The letter was sent to parents following the case of Barry McCluskey, 39, from King's Park.
The former nurse posed as a 14-year-old girl to entice children to perform sex acts in front of web cameras.
McCluskey pleaded guilty to 49 charges stretching back to 2003, including lewd and libidinous practices and behaviour, at the High Court in Glasgow in February.
The Scottish Parent Teacher Council said the letter to parents was not needed and unwise.
Chief executive Eileen Prior said: "Creating a link between school uniform and paedophilia seems to be a dangerous and unhelpful one for everyone involved.
"It implies that young people are in some way responsible for the activities of paedophiles, which is an extremely dangerous argument and one which has echoes of the comments sometimes made around rapists and women's dress.
"If there is evidence of activity by a paedophile in the area, then police and parents should be informed and involved."
She added: "Many parents - and indeed young people themselves - are keen to have a dress code in school which requires everyone in the school community to dress in a way which is appropriate for a working environment."