A father and his five-year-old son were turned away from their local swimming pool because they were the wrong religion.
David Toube, 39, and his son Harry were told that the Sunday morning session was reserved for Muslim men only.
Hackney Council, which runs the Clissold Leisure Centre in Stoke Newington, north London, claimed staff there had made a mistake.
However, the Muslim-only session was advertised on its website.
Mr Toube, a corporate lawyer, described his experiences on a blog.
"I arrived at the pool to discover that they were holding what staff described to me as "Muslim men only swimming"," he wrote.
"I asked whether my son and I could go as we were both male. I was told that the session was for Muslims only and that we could not be admitted. I asked what would happen if I turned up and insisted I was Muslim.
"The manager suggested that they might ask the Muslims swimming if they minded my son and I swimming with them. If they didn't object, we might be allowed in."