PARIS - US technology giant Apple said Friday it had seen no evidence that overheating batteries had caused screens on some of its iPhone devices to explode, blaming incidents in France on "external force."

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.

"To date, there are no confirmed battery overheating incidents for iPhone 3GS and the number of reports we are investigating is in the single digits," the firm said in a statement to Agence France-Presse.

"The iPhones with broken glass that we have analysed to date show that in all cases the glass cracked due to an external force that was applied to the iPhone," the company added.

Ten French consumers have come forward to say their iPhone screens exploded or cracked without explanation, according to an Agence France-Presse 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.