An investigation is under way into how a fake bomb was transported on a cargo plane from the UK.
The UPS flight travelled to Turkey without the suspicious device being detected.
The Department for Transport said it was taking the matter "very seriously".
A Turkish man delivered the package, which had a timer, wires and detonator and was placed inside a wedding cake box, to a UPS office in north London a fortnight ago, according to ITV News.
A Department for Transport spokesman said: "The Government is aware of this incident and takes it very seriously.
"We have already begun an investigation which will look at all aspects of this incident, including UPS's procedures.
"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."
Last October 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 (10.58oz) of the powerful explosive PETN.