Unknown suspects in Yemen hid bombs inside printers and shipped them to addresses in Chicago [Reuters]

A mail bomb intercepted last month at an English airport was timed to explode over the east coast of the US, according to UK police.

Forensic evidence showed the device, originally sent from Yemen, was set to detonate about seven hours after the cargo aircraft carrying it left the UK for the US, British police said on Wednesday.

The package was removed by police at central England's East Midlands Airport during transit after a tip-off from the Saudi intelligence service.

"If the device had not been removed from the aircraft, the activation could have occurred over the eastern seaboard of the US," police said in a statement.

Authorities on both sides of the Atlantic said they only narrowly thwarted the plot, in which unknow suspects in Yemen hid two powerful bombs inside printers and shipped them to addresses in Chicago.

After the first bomb was intercepted at East Midlands Airport another one was discovered at a FedEx cargo facility in Dubai.

The Yemen-based al-Qaeda in the Arabian Peninsula has claimed responsibility for the bombs and has vowed to send more explosives-packed parcels.

The exact aim of the attack is unclear, but a US official had said evidence points to a plot to blow up cargo planes inside the US, either on runways or over American cities.

Source: Agencies