Blank passports and visas worth £2.5 million on the black market have been stolen from a delivery van.Police are looking for at least two suspects after they made off with 24 brown cardboard boxes measuring around 5in (13cm) by 4in (10cm) when the delivery driver stopped off at a newsagents.The documents were destined for British embassies and were being transported from a factory in Oldham to RAF Northolt in northwest London.One of the raiders jumped in while the driver was away from the vehicle in Oldham, Greater Manchester. A second delivery man sitting in the van was then attacked and the offender sped off.Detective Chief Inspector Bill McGreavy said: "The actual value of the passports themselves is around £2.5 million."He said he had no significant information to suggest it was a targeted theft, adding: "The commodity stolen is unusual. Whether the commodity was the intended items I don't know. The offenders in this incident have not taken all the items from the van. They've not cleared the van out."Mr McGreavy continued: "The passenger has told us that both doors were opened simultaneously so I think there was a minimum of two offenders."He described one suspect as a tanned male with an English accent and dark hair.He said this description related to a man who held open the passenger side door of the delivery van."The passenger had his head forced down into the dashboard. The van then moved along Long Lane. He heard noises at the back of the van."After two to three minutes he lifted his head up, and couldn't see anybody. He then found the driver, who was looking for him. They then discovered that items had been taken from the back of the van."Mr McGreavy said police did not believe weapons had been used."The police are trying to put together the movements of that van and movements of staff from leaving the depot. We do want to discover what the normal routine was with regard to this pick-up and delivery."The van is currently being forensically examined, he said.Mr McGreavy reassured the public that the hi-tech passports contained a microchip which can be encrypted, "so they're very secure passports".He added: "I'm appealing to anyone who was in the vicinity of Long Lane, Chadderton."Did they see a white Citroen transit van? Did they see a driver who was looking for his van? Did they see anything suspicious?"If anybody did see anything, no matter how small, ring police on 0161 856 8951."