One of two mail bombs sent from Yemen last week was disarmed just 17 minutes before it was set to go off, the French interior minister said Thursday, but American and British officials said they had no information that would confirm that.
White House press secretary Robert Gibbs 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. U.S. investigators also said they were unable to confirm the French report.
A senior U.S. official told Fox News on Thursday that both bombs contained cell phone detonators that were timed to the alarm function. The official said that the bombs were constructed to have the alarm trigger power from a battery that would in turn heat lead azide -- a chemical initiator -- in a syringe. Once hot, the lead would then cause PETN explosives -- packed into each printer cartridge -- to detonate.
The official said the syringe was the same style of detonator that master bomb maker Ibrahim al-Asiri used in the failed bombing last Christmas of a Detroit-bound airliner.
"Al-Asiri has been working with PETN for a long time and in this latest venture, he is showing how creative he has become," the official said.
A government official in Britain said the device found there 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 Hortefeux's remark was not an description of the bomb found in that country.
The question of when the bombs were set to go off is central to the investigation because it could indicate whether terrorists hoped to blow up the planes over U.S. airspace or whether they simply wanted to take down the planes regardless of their location.
"One of the packages was defused only 17 minutes before the moment that it was set to explode," French Interior Minister Brice Hortefeux said. He made no other statement about the Yemen bomb plot during an interview on France's state-run France-2 television that focused on other security-related matters.
"If this was a reference to the device found in the Federal Express (Fedex) site in Dubai, then it is not correct," the source in the United Arab Emirates who is familiar with the investigation told the Associated Press. The security source was not authorized to discuss the case publicly and could not be named. The British government official also was not authorized to speak publicly of the case and could not be named.
Hortefeux did not say where he got the information about the timing, although U.S. and European intelligence officials have been exchanging information on the plot. The French Interior Ministry would not elaborate on Hortefeux's comment. The minister was said to be in meetings throughout the day.
Sweden's Foreign Ministry, meanwhile, changed its travel recommendations for Yemen, advising Swedes on Thursday to refrain "from all travel to Yemen until further notice." The ministry cited conflicts in Yemen's north, unrest and kidnappings in the south, and "repeated terror actions against foreigners and foreign interests."
When investigators pulled the Chicago-bound packages off cargo planes in England and the United Arab Emirates Friday, they found the bombs wired to cell 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 the alarm or timer functions to detonate the bombs, U.S. officials have said.
The bomb found at East Midlands airport in central England went unnoticed for several hours.
Investigators have centered on al-Asiri, the Yemeni Al Qaeda faction's top bomb maker, who had previously designed a bomb that failed to go off on a crowded U.S.-bound passenger jetliner last Christmas.
This time, authorities believe that al-Asiri packed four times as much explosives into the bombs hidden last week on flights from Yemen. The two bombs contained 300 and 400 grams of the industrial explosive PETN, according to a German security official, who briefed reporters Monday in Berlin on condition of anonymity in line with department guidelines.
By comparison, the bomb stuffed into a terrorist suspect's underwear on the Detroit-bound plane last Christmas contained about 80 grams.
One of the explosive devices found inside a shipped printer cartridge in Dubai had flown on two airlines before it was seized, first on a Qatar Airways Airbus A320 jet to Doha and then on an as-yet-undisclosed flight from Doha to Dubai. The number of passengers on the flights were unknown, but the first flight had a 144-seat capacity and the second would have moved on one of a variety of planes with seating capacities ranging from 144 to 335.
The packages were addressed to two Chicago-area synagogues. Because the addresses were out of date and the names on the packages included references to the Crusades -- the 200-year wars waged by Christians largely against Muslims -- officials do not believe the synagogues were the targets.
Fox News' Catherine Herridge and the Associated Press contributed to this report