AceShowbiz -

A truck containing sound equipment for Madonna's MDNA roadshow has overturned on a highway in Sweden while on its way to Goteborg for her next tour stop. At least one person has been injured in the accident and three cars were damaged.

Some of the sound equipment may have been damaged but according to Christopher Akesson, a spokesman for Live Nation, there are no signs that the tour is in any kind of trouble. "I suspect that if there was anything serious, we would have had information about it by this time," the rep said.

Police said that the cause of the accident was unclear. Report suggested the singer fortunately didn't board the vehicle.

Madonna's tour has constantly been on news mostly due to her stage antics. The veteran singer flashed her right nipple during her show in Istanbul, and showed off her thong-clad butt in Rome. In a separate show, this time in Tel Aviv, Israel, she sang "Nobody Knows Me" with a photo of Marine Le Pen projected on a giant screen. The leader of the French National Front wore a swastika on her forehead.

This is the 53-year-old singer's ninth world tour to date and it is part of promoting her latest album, "MDNA". The Queen of Pop will continue traveling across Europe until August 21 before flying back to North America for another series of live concerts.