According to SquareTrade, a company that provides extended warranties for iPhones, the iPhone 4 from Apple is "significantly more prone to physical damage" than the iPhone 3GS released last year.

The warranty company said that in the first four months since the release of the iPhone 4, the smartphone has 82% more claims for shattered screens compared to iPhone 3GS figures from the summer of 2009.

In interview with ComputerWorld, Vince Tseng, vice president of marketing for SquaeTrade, said that the handset's glass back may be causing the surge in claims.

"You now have twice as much glass to scratch or break," Tseng said. Previous iPhone models such as the 3GS had a plastic back.

According to SquareTrade figures, 3.9% of iPhone 4 owners who have filed warranty claims in the first few months since the release of the handset have complained of a cracked screen. Only 2.1% of iPhone 3GS owners made similar complaints.

In its Web site, Apple claims that the aluminosilicate glass found on the front and the back of the iPhone 4 handset is 30 times harder compared to plastic.