The 'Voice' judge's track 'Let's Go', which also features fellow rapper Chris Brown and appears on his forthcoming album Willpower, is apparently similar to 'Rebound', a dance song produced by the UK pair, reported Digital Spy.
After Mat posted a YouTube link of 'Let's Go' on Twitter, Arty tweeted, "LOL what? They never cleared rights through Anjunabeats, who's only one label, who ownes the rights for Rebound (sic)."
Mat later wrote om his Facebook page, "I really and truly appreciate all the support you (fans) are giving me and Arty in response to Will.I.Am's copyright infringement. However, this doesn't excuse the horrific abuse you're sending the way of will.I.Am and Chris Brown, and it especially doesn't excuse being racist."