RIM announced on Feb. 20 that DoCoMo was starting to sell the Blackberry Bold. (Research in Motion)

A smartphone model launched in Japan last week by Research in Motion has been pulled from shelves after customers said the devices were hot — but not always in a good way.

Waterloo, Ont.-based RIM confirmed in a statement Friday that it and NTT DoCoMo, the Japanese wireless service provider that had been selling the phones, were voluntarily suspending sales of the Blackberry Bold while they investigated reports that some were overheating.

The statement said a "small number" of the phones sold by DoCoMo in Japan since they were launched on Feb. 20 were getting unusually warm during charging but the temperatures "appear to have remained within the safety range of regulatory standards."

RIM said it has already ruled out a battery problem, but is still investigating the root cause.

The problem does not affect sales of Blackberry Bold devices in other countries, the company said.

"The companies hope to renew sales in Japan soon," the statement added.

RIM had announced last week that NTT DoCoMo, which has 54 million customers in Japan and bills itself as one of the world's largest mobile communications operators, would begin making the Blackberry Bold available through all its corporate and retail outlets across Japan. The Japanese version included a specially designed keyboard with support for Japanese text input.

According to RIM's website, the Blackberry Bold is sold in 29 countries around the world. The phone's available features include built-in GPS and maps, Wi-Fi support and a video recorder.