The launch of Diablo III stole players away from World of Warcraft, says Blizzard boss Mike Morhaime.

Speaking at Blizzard’s investors call, Morhaime also noted that it was common for the game to lose subscribers near the end of an expansion cycle.

"We saw a similar drop in subscribers in the months before Cataclysm, followed by a substantial return of players around the Cataclysm launch. We're also seeing that a number of players took a break from WoW to play Diablo III," he said.

Morhaime also took the opportunity to address the problems his company had during the Diablo III launch.

"While Diablo III was our fourteenth number one seller, we did experience some challenges. Due to the unprecedented influx of players a number of service issues arose that we needed to work around the clock to address.”

“The vast majority of these issues were ironed out within a couple weeks of launch. As I mentioned in a letter to players recently, we're not satisfied with just breaking launch records. We want people to play and enjoy Diablo III for a long time," he said.

"We've already made a number of fixes and updates, including activation of the auction house... and the Diablo team has also been working on improvements to in-game rewards and having a player versus player mode which we hope will enhance the value and longevity of the game."

The next WoW expansion, Mists of Pandaria, is out on September 25.