50 Cent has taken Taco Bell to court over claims the U.S. fast food firm used his name in an advertising campaign without his permission.

In a lawsuit filed in Manhattan federal court on Wednesday, the rapper, real name Curtis Jackson, accused the chain of "diluting the value of his good name" by using it in conjunction with its 79-89-99 Cent Why Pay More campaign, thereby fooling customers into thinking he had endorsed the franchise.

In an open letter widely published in June, Taco Bell bosses offered to make a $10,000 donation to a charity of 50 Cent's choice if he agreed to change his name for one day. They stipulated he must stop by one of the chain's restaurants and rap his order at the drive-thru window - using a new moniker: 79 Cent, 89 Cent or 99 Cent.

50's court documents read: "Without seeking or obtaining Jackson's authorization, defendant Taco Bell made him the star and focus of its nation-wide advertising campaign by using his name, persona and trademark to promote Taco Bell's business and products.

"As Taco Bell intended, many customers believed that 50 Cent had agreed to endorse Taco Bell's products. Indeed, postings on numerous Internet 'blogs' castigated 50 Cent for 'selling out' by his apparent endorsement of Taco Bell."