Will.i.am has defended Justin Bieber after a controversial visit to Amsterdam.

The 'Beauty and the Beat' hitmaker went to the Anne Frank Museum last week and was criticised for writing in a guestbook hoping the Holocaust victim ''would have been a belieber''.

Now the Black Eyed Peas star - who collaborated with Justin on new single '#thatpower' - has told people to not be so hard on the 19-year-old singer and insisted he could have done a lot worse in the city.

Speaking to The Sun newspaper, he said: ''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 record producer also described Justin as ''one of the best'' artists he's worked with, and explained he is under a lot of pressure growing up.

He 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.''