Infinity Ward studio head Vince Zampella has revealed that the company’s Call Of Duty 4 has now sold 10 million copies worldwide, across the Xbox 360, PlayStation 3 and PC formats.

A breakdown of sales by format was not provided, but speaking to website News.com, Zampella did indicate that the Xbox 360 version was the most successful. The game’s sales makes it one of the most successful of all time, with the title selling comparably to entries in the Grand Theft Auto, The Sims, Super Mario Bros. and Pokemon franchises.

Infinity Ward claims that Call of Duty 4 is one of “less than ten” games to reach the ten million mark since 2000, outselling each of the three Halo titles and all of the Mario Kart games thus far.

Additionally, the downloadable Variety Map Pack is now revealed to have sold 1.5 million copies, after Activision said it had sold over one million in its first nine days of availability. As of April 18th, 2008 over 30 million sessions and more than 30 million hours of gameplay had been logged by users playing online.

Zampella admitted that producing another 10 million selling title would prove difficult, with the next game in the franchise, Call of Duty 5, in production by Call of Duty 3 developer Treyarch.