50 Cent, who is in a much-hyped battle of album sales with Kanye West, has canceled several performances in Europe. MTV News said the 31-year-old rapper canceled performances at the MOBO Awards and the Vodafone Live Music Awards, both in London on Wednesday, and a performance for MTV in Germany on Friday.

No details were posted on the rapper's Web site, and Polydor Records, 50 Cent's record label in Britain, wasn't immediately available for comment Monday.

MTV said the rapper canceled the appearances due to changes in his schedule.

50 Cent, whose real name is Curtis Jackson, had said he'll retire as a solo artist if West's new album, "Graduation," outsells his latest CD, "Curtis," in first-week sales.

West, 29, beat 50 Cent to the No. 1 spot on Britain's album chart Sunday, with 50 Cent in the No. 2 spot, the Official UK Charts Company said on its Web site. No sales figures were posted. U.S. sales figures will be available this week.