The Voice UK coach will.i.am has defended his pal Justin Bieber after a controversial visit to the Anne Frank Museum in Amsterdam.

The 'Boyfriend' hitmaker visited the Anne Frank Museum last week and was criticised for writing, "Anne Frank would have been a belieber," in the guestbook.

The Black Eyed Peas star recently collaborated with Justin on new his single '#thatpower' and said that Bieber "could have done worse" in the iconic city.

He told The Sun newspaper, ''The dude was in freaking Amsterdam. He could get sex because it's legal, he could get drugs because it's legal, and now we are making a hoopla because he said, 'I wonder if Anne Frank had been a belieber'.

''He went to a museum! If you go to Amsterdam you are going to see some crazy freaking s**t, you are going to see some titties, there is a lot of s**t to do in Amsterdam but he chose to go to Anne Frank's house.''

The 38-year-old producer added, ''Justin is a great talent. Of all the people I have worked with over the past five years he is one of the best.

''I remember when I was 19, it was pretty tough. The difference between me and him is that I got to grow up in private, he is growing up in front of everybody.''

Watch will.i.am's video featuring Justin Bieber for "#thatpower" here: