Thirteen soldiers were injured when a military truck in which they had been travelling overturned near the town of Haskovo on the night of August 1 2007.

The four most severely injured soldiers were transported to Sofia’s Military Medical Academy, Focus news agency reported. The soldier in the worst condition had a fractured skull. Others had internal injuries and broken bones. The soldiers were all due to undergo surgery on August 2 2007.

Another nine soldiers injured in the accident were admitted to hospital in Haskovo.

Sixteen people were travelling in the vehicle, which overturned, most probably because of the slippery surface. Three soldiers were examined and sent home, Focus said.

Military police are investigating the accident.