Sales of the Wii U have been fine but might have been hurt by a shortage of Premium consoles, says Nintendo president Satoru Iwata.

Speaking with Reuters, Iwata said that there were challenges associated with releasing two models at the same time.

“Specifically, inventory levels for the premium deluxe package were unbalanced as many people wanted that version and couldn't find it," he said.

“But sales are not bad, and I feel it's selling steadily."

Nintendo has not released sales figures for the Wii U, but Japanese magazine publisher Enterbrain has suggested the console sold around 638,000 units in Japan between December 8 and 30.

Major US retailer GameStop is reporting that it sold 320,000 Wii U units in the period between its launch on November 18 and December 29, 2012.

Last October, Nintendo said that it was aiming to sell 5.5 million Wii U consoles by the end of March 2013.

According to VGCharts, nearly 2.5 million Wii U consoles have been sold to date.

Official figures from Nintendo are expected at the end of this month.

Nintendo's share price has dropped 15 per cent since the launch of the Wii U.