Japan’s largest cell service provider, DoCoMo, has suspended sales of the Blackberry Bold smart phone following reports that the device can overheat during recharging.

The company reports that it has sold about 4,000 of the new phones and, of those, about 30 users have reported overheating problems.

Apparently, the phone’s keyboard area can heat up alarmingly. However, DoCoMo says it’s had no reports of users being burned or units catching fire.

BlackBerry maker Research In Motion (RIM) says it’s ruled out problems specifically associated with the Bold’s battery but has not yet determined just what is causing the overheating problem.

RIM was quick to state that the overheating problem appears to be confined to Bolds sold in Japan in the past week or so and that the problem does not seem to effect Bolds being sold in other markets.