A head teacher has warned that a row about tight-fitting trousers was a distraction for a school trying to make progress.

Christopher Bennet, head of St Peter's School in Huntingdon, said the issue was about the expectation that students would wear the correct school uniform.

He said some girls were wearing tight-fitting leggings which were not part of the approved uniform.

Social media has seen a string of complaints from parents saying St Peter's had launched a clampdown on the wrong type of trousers and pupils who wore them were being given detention.

Amy Moule, 37, whose daughter Bethany, 15, is a student at the school, said: "I would rather my daughter got an education than worry about trousers.

"At a point in their lives when they are studying for exams in Year 11 and at a critical time in their lives when body is an issue, they are being put under undue pressure."

Miss Moule, who has organised an online petition signed by about 200 people, said education should not be affected by trousers which were smart and black.

But Mr Bennet said: "It is all about expectation. Some girls are coming in in leggings."

He said parents had been told before the start of the term about the type of clothing considered to meet uniform requirements.

"We even sent pictures out showing what was appropriate and what was not appropriate," Mr Bennett said. "We have made our stance and, unfortunately, a small number of people don't like it.

"We have 1,002 children and this only affects 25, which is 2.5 per cent of the students."

He said the appropriate loose-fitting trousers could be bought through the school and were also available through High Street stores.

"It's not about where they come from, it is about what they are," Mr Bennet said.

He said pupils who were disciplined for breaching the uniform code would not miss out on their education and that staff members would be sent home to change if they wore inappropriate clothing.

"We expect professional attire," Mr Bennet said.

Miss Moule said there were inconsistencies in the way sanctions were applied and that the same trousers could look different on individual students because of their shapes.

"I don't think it is enough of an issue to give them detention," she said.

She said some parents could not afford to buy new trousers and she would have preferred to see the rules phased in. On Facebook one mother said her daughter had been wearing the same style since Year 7 without problems. Another said the issue had taken over her life and, while she was all for following rules, the official trousers were not fit for purpose. Other parents said their daughters' trousers had been approved by one teacher but had been threatened with detention by another.