Amanda Seyfried has refused to confirm whether she is dating Ryan Phillippe.

The 'Mamma Mia!' star was spotted leaving Kate Hudson's Halloween party in Los Angeles with the Hollywood heartthrob on Saturday night (30.10.10), and has done little to eliminate rumours the pair are now an item.

When asked by photographers if they were romantically linked, Amanda replied: "You never know!"

At the time, an onlooker explained Ryan - who was married to actress Reese Witherspoon until 2007 - was being "really sweet" around the blonde beauty.

The insider said: "They were laughing and chatting with other people at the party and were obviously a couple.

"Ryan was really sweet with her - he had his hand on her lower back for a while when they were talking to another couple. They looked great together."

Amanda parted ways with British actor Dominic Cooper in June, after the couple first met on the set of 'Mamma Mia!' while he was still in a relationship with another woman.