Blank passports stolen from a van while the driver went into a shop have a black market value of £2.5 million, police have said.
The documents were being transported in an unarmoured white Citroen van from Oldham, Greater Manchester, to London when the hijackers struck. Passports are normally transported using armoured and secure vehicles - with drivers not allowed to make unauthorised stops.
But the Foreign and Commonwealth Office (FCO) was in charge of this delivery as the 3,000 passports were destined for embassies abroad. Officials at the FCO admitted it was a serious security breach.
A firm was subcontracted to deliver them from 3M Security Printing & Systems in Chadderton to RAF Northolt.
Just minutes into the journey on Monday morning the robbers pounced as the driver stopped off at Yogis Newsagent and Off Licence to buy a newspaper and a chocolate bar.
One of the raiders jumped in and the second delivery man in the passenger seat was attacked before the offender sped off with the vehicle.
Labour Deputy leader Harriet Harman said the robbery was a "serious crime" but did not necessarily show a "sloppy attitude".
But Shadow Home Secretary Dominic Grieve said: "This latest security failure is all the more shocking, given the Government's inability to learn the lessons from the HMRC fiasco and a string of other government failures to secure confidential documents and personal information."
Police said there was nothing to suggest it was a targeted theft - but the passports were snatched while other items were left in the vehicle.
"The actual value of the passports themselves is around £2.5 million," said Det Chief Insp Bill McGreavy, of Greater Manchester Police.
