PARIS: US technology giant Apple rejected reports Friday that overheating batteries had caused some of its iPhone devices to explode in users' hands, blaming incidents in France on "external pressure".

French authorities have opened an investigation into the safety of the cult smartphone, following claims by several users in France and elsewhere that their iPhone screens had shattered in a dangerous manner during use.

"As of today, there has been no confirmed incident linked to battery overheating in the iPhone 3GS, and the number of cases we are investigating amounts to less than a dozen," the firm said in a statement to AFP.

"The iPhones with broken screens that we have been able to analyse so far show, in all cases, that the cracks were caused by an external pressure upon the iPhone," the company added.

Ten French consumers have come forward to say their iPhone screens exploded or cracked without explanation, according to an AFP tally, including a case in mid-August in which a teenager was said to have suffered an eye injury.

Apple's commercial director in France, Michel Coulomb, met the country's consumer affairs minister Herve Novelli on Friday to discuss the probe launched by a state safety agency following consumer complaints.

Afterwards, Novelli confirmed Apple's interim findings, but said it was too soon to apportion blame or say whether the users themselves had been responsible for the damage.

"The first results show, according to Apple management, that the iPhones weren't damaged by a battery defect leading to an explosion, but that there had been a prior shock that cracked the screens," the minister said.

He added that in the case of the eye injury, the injured party had so far refused to hand over the phone to Apple's management for testing, so it was not year clear what had caused the incident.

Apple has sold 26 million iPhones and 200 million iPods around the world.