A release date or price has not been announced for the next expansion.

But, Kevin Kelly of games site Joystiq said that World of Warcraft (WoW) players may need to have a copy of the first expansion to play Wrath of the Lich King.

"Blizzard isn't sure if this will require an additional purchase, or if they will bundle it in at no extra cost," he wrote.

Fantasy world

WoW was launched in 2004 and has become one of the world's most popular massively multiplayer online role-playing game with more than 9 million subscribing players.

It is set in the fantasy world of Azeroth and players spend their time turning their initially weak warriors, warlocks, rogues and others into more powerful characters by killing monsters and looting them for items or money.

Players pay a monthly fee to subscribe in addition to the cost of buying the CD of the game.

The addition will introduce a new continent called Northrend populated by the armies of the Lich King.

The continent will be familiar to players of the PC game Warcraft III: The Frozen Throne.

"This expansion will add some of the most infamous characters and settings from the Warcraft Universe to the World of Warcraft," said Mike Morhaime, president and co-founder of Blizzard Entertainment.

Gamers will also be able to choose new professions and new looks for their characters.

A player-v-player mode will see the introduction of siege weapons and destructible buildings. "Wrath of the Lich King will introduce a number of features specifically requested by players over the past couple of years," Mr Morhaime added.

Blizzard Entertainment said it would release more details about the expansion as it was developed.