One of two mail bombs sent from Yemen last week was defused just 17 minutes before it was set to explode, the French interior minister has said.
Brice Hortefeux provided no other details in an interview with France's state-run France-2 television, or say where he got the information from.
When investigators pulled the Chicago-bound packages off cargo planes at East Midlands Airport and at Dubai on Friday, they found the bombs were wired to mobile phones and hidden in the toner cartridges of computer printers.
The communication cards had been removed and the phones could not receive calls, officials said, making it likely the terrorists intended to use the alarm or timer functions to detonate the bombs.
They also said that each bomb was attached to a syringe containing lead azide, a chemical initiator that would have detonated PETN explosives packed into each printer cartridge.
Both PETN and a syringe were used in the failed bombing last Christmas of a Detroit-bound airliner.
Investigations have centred on the Yemeni al Qaida faction's top bomb maker, who had previously designed the bomb that failed to go off on a crowded US-bound passenger jetliner last Christmas. This time authorities believe that master bomb maker Ibrahim al-Asiri packed four times as much explosive into the bombs.
The two bombs contained 300 and 400 grams of the industrial explosive PETN, according to a German security official. By comparison, the bomb stuffed into a terrorist suspect's underwear on the Detroit-bound plane last Christmas contained about 80 grams.
White House press secretary Robert Gibbs later said the question of when the bombs found in Britain and the United Arab Emirates were to go off was still under investigation and there was no information confirming such a close call. US investigators also said they were unable to confirm the French report.
A Government official in Britain said the device found at East Midlands was still undergoing forensic tests and it had not been determined how close it was to being detonated. A security source in the United Arab Emirates said Mr Hortefeux's remark was not a description of the bomb found at Dubai.