Nintendo shares fell by as much as 18% in Japan as investors responded to a profit warning from the gaming giant.

On Friday, Nintendo said it would suffer a ¥35bn (£200m) operating loss for the current financial year, compared with an earlier forecast of a ¥100bn operating profit.

The shock announcement from the owner of Super Mario and Donkey Kong was caused by disappointing sales of the 3DS handheld player and the Wii U console outside Japan, despite heavy spending on promotions and advertising.

The shares fell by almost a fifth but then staged a partial recovery to close down 6.2% after the Nintendo president, Satoru Iwata, said he would review the company's strategy.

Nintendo has refused to license its software characters such as Super Mario and Zelda for use on other companies' products. But analysts said the company had to face changes to the market wrought by the rise of smartphones and tablets.

Iwata said: "Given the expansion of smart devices, we are naturally studying how smart devices can be used to grow the game-player business." But he added: "It's not as simple as enabling Mario to move on a smartphone."

Strict control over Nintendo's characters helped make it the market leader when it launched Wii in 2007, but gamers have turned to smartphones, tablets and faster consoles from rivals Sony and Microsoft.

Nintendo reduced its sales forecast for the year ending 31 March to 2.8m Wii U units from an earlier estimate of 9m. It halved its forecast for game sales for the system to 19m.