Shipping company UPS has been barred from moving air cargo through some U.K. facilities because of security deficiencies, the British government said Friday.
The Department for Transport disclosed the action but gave no information on the security issues and didn't identify the locations involved.
"Following careful consideration, the department has restricted the number of sites in the U.K. at which UPS are permitted to screen air cargo until it has satisfied current security requirements," it said in a statement.
The department said it could not give any details of the sites for security reasons.
UPS told customers Friday that shipments from Britain were being delayed. It said "areas of concern" were found during a government review of "UPS procedures and employment documentation related to security."
"Some facilities have been temporarily taken offline, which in some cases has led to delays in the movement of packages," UPS told the BBC. "UPS has activated contingency plans, communicated with customers and expects service levels to return to normal early next week."
No other air freight companies were mentioned in the U.K. government statement.
The vulnerability of air cargo to terrorist attacks is a major worry for international security agencies.
Last October, two bombs were sent disguised in toner cartridges on cargo flights from Yemen bound for the United States. One was discovered at a FedEx cargo facility in Dubai, the other at a UPS depot at England's East Midlands Airport, 100 miles (160 kilometers) north of London.
Officials said the bombs were viable and could have exploded in mid-flight. Al-Qaida was blamed for the plot, which was foiled by a tip-off from Saudi intelligence.
Britain suspended all unaccompanied air cargo from Yemen and Somalia after the thwarted plot, and officials in Britain, the United States and other countries promised to tighten air cargo security.
Despite the heightened alert, in March someone shipped a hoax bomb — which had a timer, wires and a detonator — to Turkey via the UPS office in London.
Philip Baum, editor of Aviation Security International, said that since the toner cartridge plot "there has been a greater focus on air cargo security regimes, but that does not mean a great deal has changed."
But he said the UPS restrictions should be seen as positive.
"It means that problems have been found and are being rectified," he said.