Subscribers to the online adventure game World of Warcraft have dropped dramatically this year, publisher Activision Blizzard has said.

The company said 14% of users left the game between January and March - a fall of 1.3 million.

The majority of lost users were in the East, despite the company making efforts to appeal to those markets, with recent upgrades.

Activision told investors to expect subscriber figures to dip further.

Shares in the publisher fell by about 5% on Wednesday, following the news.

The California-based company blamed the rise of free-to-play games.

Uncertainty around new consoles due from Microsoft and Sony - and the "very slow start" of Nintendo's newest offering, the Wii U - had contributed to what will be a challenging 2013 for the company as a whole, chief executive Bobby Kotick said.

He told investors on Wednesday: "It's important to note that the nature of online games has changed, and with the environment becoming far more competitive.

"To address this, we're working to release new content more frequently to keep our players engaged longer and make it easier for lapsed players to come back into the game."

BBC News