A Muslim school in Wilmington has sued the city, alleging a “pattern of discriminatory treatment” after children were asked to leave a public pool for wearing cotton clothing.

The lawsuit, filed Wednesday in the Delaware Court of Chancery, claimed “ongoing discrimination” by municipal employees at the Foster M. Brown Community Pool, and faulted Wilmington Mayor Mike Purzycki and the city’s parks and recreation director for enforcing a policy that allegedly singled out Muslim students for dressing according to their religious beliefs.