(Cover) - EN Showbiz - Ashton Kutcher says a towel is your best friend when shooting sex scenes.

The actor stars alongside Natalie Portman in new movie No Strings Attached, about two lifelong friends who take their relationship to the next level. While the pair vow just to have fun together things soon become awkward when feelings get involved.

The subject matter means Ashton and Natalie had to shoot a lot of love scenes, which they admit was embarrassing.

At a certain point you just let it flow It becomes really technical. The towel is your best friend, man. You can't go wrong with a good towel. I was sort of requesting a bigger towel [for one particular scene], but they left me with a hand towel, he laughed.

Natalie added: We obviously had to do stuff that could be really awkward, and when you just know that the person there won't overstep boundaries, you can just play and be silly together. The whole point of any of the sex scenes is to make you laugh, so at least we had that, that we could be really ridiculous in those scenes.

Both stars found the storyline of No Strings Attached interesting, and spent a great deal of time considering it. Ashton is married to Demi Moore and Natalie recently announced she is expecting a baby with fianc Benjamin Millepied, so they find it hard to relate to people who arent in a committed relationship.

Neither is convinced such an arrangement would actually work, as it would be so hard to separate physical and emotional feelings.

I wouldn't know, Ashton laughed to ETOnline. I doubt that that kind of thing can be pulled off I think that there are friend feelings that are involved that are going to intercept the ability for it to be just completely detached.

I think some people could probably handle it, Natalie mused. Not a lot of people. It's definitely hard. (C) Cover Media