London, Dec 14 - English actress Keira Knightley has reportedly stripped off to pose naked for an acclaimed artist.

The "Pirates of the Caribbean" actress, who bared all to film a bath scene with Sienna Miller in their 2008 movie "The Edge of Love", has allegedly been shedding her clothes during sessions at London's Halcyon Gallery for Mitch Griffiths, reports heraldsun.com.au.

"It's considered a great honour to be painted by Mitch. He is a highly respected nude painter and is painting a number of subjects for an exhibition next year. He is delighted Keira agreed to take part," said a source.