A campaign telling parents to send children to school if they have colds has prompted more than 6,000 signatures to a petition against its "aggressive, condescending and insulting" message.
Leaflets were sent in East Sussex County Council's "Get a Grip" drive to parents whose children missed at least three days of the current school year.
They also give advice on "being more organised" the night before school.
The council said it "won't flinch from this extremely serious issue".
'Blindly attacked'
The "Get a Grip" campaign features the slogan "good reasons for missing school - there are none".
The petition, set up by Ella Lewis of Seaford, calls for the council to withdraw the campaign and apologise "for the insulting treatment of and attitude towards parents".
It states families feel alienated and "blindly attacked" by the campaign, especially those "struggling with serious illnesses, traumas and ongoing disabilities and conditions".
The petition adds: "Of course we don't want our children to miss the curriculum, and of course we don't want teachers wasting their time catching children up
instead of teaching the class, but there is nothing we can do about it."
The leaflet sent out to parents warns them about fines for unauthorised absences, including holidays during term time, and says children should attend school if they have a cold, headache or minor illness.
It also gives advice on "being more organised" in preparing for school the night before.
A council spokesman said the campaign was not aimed at parents of children who had genuine medical reasons for being absent, but for those who regularly have odd days off or holiday in term time.
He added: "We appreciate this campaign has been controversial.
"Missing even one day of school has an impact not just on a child's education but on the rest of the class, as it means the teacher has to spend time helping them catch up - to the detriment of other pupils. Missing days of school reduces children's chances of achieving success.
"The use of the hair grip was just to get people's attention. We're not suggesting children aren't going to school because they can't find a hair grip in the morning."