The company added however, that these instances were rare.

At the same time Nokia urged the owners of its handsets to only buy original replacement batteries to avoid such explosions.

Most of the incidents were caused by a short circuit in the batteries after they had been dropped to the ground, Jonas Geust, a senior engineer with Nokia, told reporters on Thursday.

He added that all original batteries had safety measures to prevent them from short-circuiting, and that so far all explosions involving Nokia mobile phones were caused by either counterfeit or non-original power packs.

Earlier this month, a Finnish woman was hospitalised after her Nokia phone exploded when she dropped it on the floor, and recently there were similar cases in Vietnam and The Netherlands as well, the firm said.

Belgian report

Last week Belgian consumer watchdog Test-Aankoop announced in a widely distributed report that several Nokia batteries it had tested lacked the necessary safety measures to prevent them from exploding.

It soon withdrew its test results however when it became clear that several of the batteries it had tried out were counterfeits.

Nokia said the episode proved both how difficult it was to distinguish original products from pirated ones and how tough it was to keep the latter off the market.

It added, however, that the best way for consumers to ensure that they are purchasing original batteries is to only buy them at a Nokia authorized dealer or another reputable outlet.

Nokia has sold more than 400 million phones worldwide.