'Too flimsy'

Many blogs have reported that the Wiimote strap is too flimsy and there are accounts of the remote flying out of hands and crashing into TV screens.

Nintendo president Satoru Iwata said of the problems: "We are investigating."

He added: "Some people are getting a lot more excited than we'd expected.

"We need to better communicate to people how to deal with Wii as a new form of entertainment."

Nintendo also cautioned players to stay at least three feet away from the TV and to make sure people and objects were safely outside their range of motion.

Last week, Nintendo America chief Reggie Fils-Aime told Reuters news agency that many gamers were using big, sweeping motions where smaller ones would do.

"We literally have consumers letting go of the remote like you do a bowling ball. You can't do that." Fils-Aime said of a bowling game in its Wii Sports title.