Those hoping for a Nintendo Wii this Christmas may be disappointed, according to the BBC, with UK retailers apparently facing a struggle to keep up with demand for the popular console.

A Nintendo spokesperson told the BBC that demand for the Wii has outstripped expectations, and warned that customers may struggle to find the console on store shelves towards the end of the year. This is despite Nintendo's promise to ship an extra 3.5 million Wii consoles globally between now and the end of the year.

"The demand for Wii hardware globally has been unprecedented and higher than Nintendo could ever have anticipated," the spokesperson told the BBC.

See also: Nintendo Wii review

The Wii has already won the hearts and minds of gamers – from traditional console users to a new breed of gamer who isn't attracted to the high-end graphics and first-person shooter games that appeal to Xbox 360 and PS3 fans. Nintendo's move to include a physical element to many Wii titles through the use of the motion-sensitive Wii controller has been given much of the credit.

Earlier this month, research firm iSupply reported that the Wii had helped Nintendo overtake Sony to become the worldwide leader in video game sales. Combined game sales of the Nintendo Wii and Nintendo DS games totalled $1.2bn during the third quarter of 2007, up 31 percent from the second quarter of this year.

By comparison, combined PlayStation 3 (PS3), PS2 and PlayStation Portable (PSP) game sales totalled $1bn. Microsoft reached $318m in total Xbox 360 and Xbox 1 games sales.