Around 400 staff in Southampton City Council's children's services department received a memo telling them they should dress respectfully and 'carefully consider their work attire', the Daily Mail reported.
Women can wear trousers, informal dresses or skirts of 'reasonable' length, but 'not mini-skirts'.
'Please try to dress smartly and thoughtfully, in line with other professionals you come across in your day-to-day work, and in a way that shows respect to children and families,' it said.
Women, however, have threatened to fight the ban, as one of them said: 'Are they going to come around with a tape measure?'
'I would have thought the council has got better things to do than impose a regimented approach to what people wear,' said Mike Tucker, secretary of a union.