US trade sanctions have led game maker Blizzard to cut off access to World of Warcraft (Wow) in Iran.

Blizzard posted a statement to its player-forum site after hundreds of Iranian players said they had lost access to the game.

Access was lost recently, it said, because it had "tightened up its procedures" to comply with sanctions.

This also meant, said Blizzard, that it could not give refunds to players or transfer their accounts.