Hollywood hunk Josh Hartnett has warned up-and-coming actors against dating their co-stars.

The Pearl Harbour actor has been linked to a number of A-list stars, including Scarlett Johansson and Amanda Seyfried, in the past and is currently dating Brit Tamsin Egerton.

However, Hartnett is adamant young male movie stars should steer clear of romantic relationships with famous women.

He tells America's Elle magazine, "I don't recommend it to young actors. You can make a lot of enemies in the business that way.

"But when you work with somebody every day, it's like trial dating. You develop a fantasy about them. It doesn't always work out."

Hartnett also admits he finds it difficult to discuss his celebrity girlfriends with pals, adding, "When I dated a few very beautiful, very famous girls, I said something once - it wasn't really a complaint - and my buddy said, 'Oh my God, my diamond shoes are too tight.' He coined the phrase."