J.K. Rowling has jokingly castigated Harry Potter star Matthew Lewis for stripping off in a magazine shoot.

The Harry Potter creator admits she was shocked when she saw Lewis, who played Neville Longbottom in the film adaptations of her books, wearing just his underpants for a spread in Britain's Attitude magazine.

In a discussion with Lewis on Twitter.com, Rowling also referenced Daniel Radcliffe's 2007 theater stint in Equus, where he appeared completely naked onstage.

She wrote, "Not as bad as watching Dan in Equus, but close. Warn me next time, for God's sake... I will always support you whatever you want to do, Matthew. Now go put some clothes on... I hastily averted my eyes and read an article on Political Correctness to get over the shock."

Lewis responded to the posts, writing, "Well, this is awkward. Sorry, Jo..."