An investigation was under way last night after it emerged that a fake bomb had been transported on a cargo plane from the UK without being detected.
The UPS flight travelled from a London airport to Turkey without the suspicious device being detected.
It made the journey after a Turkish man delivered a package to a UPS office in north London, according to ITV News. The package contained a timer, wires and detonator, all of which were carefully cased inside a wedding cake box.
The incident comes just five months after a bomb disguised as an ink cartridge was found on a UPS cargo plane at East Midlands Airport. Police later said it was timed to detonate over the eastern seaboard of the United States. The bomb, and another found in Dubai, contained at least 300g of the powerful explosive PETN.
It was not clear why the package had been tested, though experts suggest it could have been performed as a trial run ahead of a potential terrorist plot. Last night a Department for Transport spokesman said it was taking the incident "very seriously". "The UK has one of the toughest security regimes for air cargo in the world. All security measures are subject to continuous review."
A UPS spokeswoman said: "Two weeks ago, a suspicious package travelled within the UPS network aboard an all-cargo aircraft from the United Kingdom to Istanbul, Turkey.
"UPS is co-operating with the UK Department for Transport's investigation of the incident. UPS has a multiple-layered approach to ensure security."