The National Consumer Affairs Center issued a warning Thursday about smartphones overheating.
There were 75 reports of smartphone-caused burn injuries in Japan and 1,032 reports altogether of smartphones overheating between April 2009 and December, the center said.
The number of reports has increased yearly, hitting a record 523 in fiscal 2012, and is expected to rise further in fiscal 2013, which will end March 31, the center said.
The center said smartphones might be at greater risk of overheating than other mobile phones as they consume far more electricity and must be charged more frequently.
It advised consumers to take care in handling charging terminals, and asked the Telecommunications Carriers Association to do more to make consumers aware of the risks and to develop smartphones invulnerable to overheating.
The center said its experiments indicated that when a broken charging terminal was used, the temperature around the terminal rose to more than 100 degrees.
Among the reported incidents, a woman in her 20s in Osaka suffered a low-temperature burn on her cheek when she used an overheated smartphone for about eight minutes.
A Saitama man in his 50s reported that after he went to bed while leaving his smartphone to charge through a personal computer, he awoke to a burning smell and found the charging terminal melted and a nearby tatami mat burned.