Nintendo Co Ltd might provide clues on the effect of the devastating March 11 earthquake and tsunami on the industry's supply chain and domestic demand as it kicks off earnings for the Japanese electronics sector on Monday.

Investors will also focus on sales of Nintendo's groundbreaking glasses-free 3D handheld games device, which the firm hopes will help keep it fight off growing competition from smartphones such as Apple's iPhone and the plethora of tablets battling for a share of the market.

Nintendo estimates it posted its lowest annual operating profit in 5 years in the year just ended, as its once world-beating Wii home console ages and Sony and Microsoft offer newer takes on the previously unique motion-controlled gaming feature.

For the year ended March 2011, the company's forecast is for profit to fall 41 percent to 210 billion yen after dropping 36 percent the previous year.

The outlook for the year to March 2012 is less certain, and Nintendo, like some other firms, may opt to avoid giving a forecast until the condition of its supply chain becomes clearer.

The quake and tsunami triggered shortages of key parts and materials produced in Japan, including silicon wafers, resins, gases and chips, that have snarled production across a range of industries.

After a three-year run of record earnings to March 2009, Kyoto-based Nintendo's margins have deteriorated sharply.

The consensus is for Nintendo to make an operating profit of 215.8 billion yen in the year to March 2012, according to the average of 8 estimates by analysts polled by Thomson Reuters I/B/E/S after March 11.

Nintendo shares have fallen about 15 percent so far this year, underperforming a broader market down about 5 percent.

(Editing by Anshuman Daga)

(The following story was corrected to show the forecast in paragraph 4 has a 41 percent fall to 210 billion yen,...not...a 10.3 percent fall to 320 billion yen)

Apple inc. Tsunami Nintendo Japan