Israeli entrepreneurs have invented an iPhone app that keeps drivers awake by bombarding them with trivia questions.

Last year, Assaf Mayer was visiting Australia and found himself on a boring nine-hour bus ride. "The driver said, 'right, who wants to play?,' connected his iPod to the speakers and started asking questions about the songs - it was great." Then a few months later, his friend, Eldad Ben Tora, was almost killed when a driver in front of him started to doze off.

The two put their heads together and came up with Drivia, which has just become available for free download on the App Store.

Before beginning a journey, drivers enter their level of tiredness, and they then start to hear questions accordingly - the more tired the driver, the faster they come. Answers are "marked" by the app's voice recognition capability.

"The idea is that the more engaged people are the more they will keep their eyes on the road," said Mr Mayer.

Questions are available in different subject areas, read by a voice actress with a Chicago accent, and cost $0.99 per 100. Mr Mayer and his colleagues hope to roll out the application to other platforms such as Android, Windows Media and standalone satellite navigation systems.

They also hope to integrate smart advertising which is played when a device's GPS facility knows it is relevant, such as promotions for coffee shops that the diver hears as he approaches them.