Investigators in Germany are probing a mysterious string of letter-bomb attacks on German food retail companies in recent days. State prosecutors in Heidelberg said late Thursday they had set up a special commission of more than 100 investigators to look into the mysterious attacks. They confirmed that an explosive had been identified and disarmed at a parcel distribution centre at Munich airport in the night between Wednesday and Thursday. The bomb, which was addressed to a food company in Bavaria, was the third in a string of attacks this week. On Wednesday, three people were taken to hospital when a letter bomb exploded at the German headquarters of discount supermarket Lidl. Around 100 people were evacuated from the administrative building at the company's head offices in Neckarsulm, western Germany. A similar explosion was also reported at a drinks company in nearby Eppelheim. "We assume there is a connection between these three parcels," said Baden-Wuerttemberg state police chief Stefanie Linz on Friday, in remarks carried by national news agency DPA. According to DPA, Germany's food federation had also warned its members to remain vigilant when receiving post. kih/dlc/rl