Bangkok : A passenger train derailed on old tracks in the mountains of northern Thailand early on Wednesday, slightly injuring at least 30 passengers, mostly foreign tourists. It was the second derailment on the popular route in a month.

The overnight train from Bangkok to Chiang Mai skidded off the tracks and seven out of 10 carriages flipped onto their sides, State Railway of Thailand governor Prapas Jongsanguan said.

The accident occurred in Phrae province’s Denchai district.

Railway authorities believed the accident was caused by old tracks that were scheduled for repair.

“From an initial investigation, the train was traveling under its limit, but the tracks at that stretch were old and in poor condition. The last carriage, therefore, skidded and brought down other cars,” Prapas told The Associated Press on the phone.

Prapas said one passenger was seriously injured. The rest suffered minor injuries and were provided free transport to their destinations.

The Bangkok-Chiang Mai train is popular among foreign tourists. A Bangkok-bound train from Chiang Mai derailed early this month, but no one was injured.

Train service heading north on the route was expected to resume later on Wednesday after the wreckage was cleared.