The next expansion for World of Warcraft has been the subject of intense speculation, ever since developers Blizzard trademarked the term "Cataclysm". Now, it appears that two new playable races have leaked - Goblins and Worgen.

Community site is quoting "multiple sources close to the situation" who say that the next expansion will be called "World of Warcraft: Cataclysm", and will allow Alliance players to play as wolf-men Worgen, and Horde players to pick Goblins.

Speculation amongst players is that Cataclysm will focus on the massive whirlpool between the game's two original continents which, according to game lore, was left behind "when the Well of Eternity collapsed into itself during the Great Sundering".

The 5-year-old game's most recent expansion, "Wrath of the Lich King" currently holds the PC sales record at 2.8 million copies sold in just 24 hours, and there are approximately 11.5 million active players in the virtual world of Azeroth.

An official announcement on exactly what the next expansion will contain is expected at Blizzcon, due to take place on 21 and 22 August.