Metallica have been awarded the prestigious Polar Music Prize in Sweden.

The American heavy metal band - founded by drummer Lars Ulrich - was presented with the gong by His Majesty King Carl XVI Gustaf of Sweden and Roger Glover and Ian Paice, of the British rock band Deep Purple.

Lars, 54, who was joined at the ceremony by bassist Robert Trujillo, gave an emotional speech about being ''outsiders'' who had been embraced by mainstream music.

He said: ''Who would have thought, when Metallica started this musical journey 37 years ago, that one day we would be standing in front of both musical royalty and actual royalty, accepting one of the most prestigious prizes that can be bestowed upon musicians?

''The type of music that we play was not supposed to be acknowledged or embraced by the mainstream, the media, or even large audiences. In 1981 when this band formed, I just wanted to play music in a collective setting and feel like I belonged to something bigger than myself.

''From the beginning, we always felt like outsiders. We always felt like somehow we were not good enough, not cool enough to be accepted by a general music audience...then an unexpected thing happened. The mainstream audience began moving closer and closer to the area where the musically disenfranchised like ourselves were hovering.

''About 10/15 years later, we found ourselves right in the middle of that very mainstream which we had felt so vengefully ostracised from. Receiving this prize solidifies the idea that no matter how alienated you feel, connecting to other people through music is not only possible but can be outright inspirational and life changing.''

He finished his speech by saying: ''And finally, while this award acknowledges Metallica's achievements of the past 37 years, as we stand here in this glorious moment, may the Danish kid in me shout out to the world 'Look Mom, we're just getting started!'''

Metallica are donating the prize money they have received to charity.

The international prize was founded in 1989 by Stig 'Stikkan' Anderson - the manager of pop legends ABBA - and recognises ''significant achievements in music''.

It is awarded to one contemporary and one classical musician each year.

Lars said it was ''an honour'' to share the award with Dr Ahmad Sarmast and The Afghanistan Institute of Music who has set up an organisation to rebuild music and support musicians in Afghanistan.

Previous winners of the prize include Sir Paul McCartney, Ray Charles, Joni Mitchell, Bruce Springsteen and Stevie Wonder.