Workers in London have been warned to be vigilant for suspicious packages after three explosive devices were sent to major transport hubs on Tuesday.
Counter-terror police investigating the packages have circulated images of two of the packages to mail sorting offices and transport workers, and warned them to be on the look out for anything similar.
Scotland Yard said it was working “to ensure the safety of the public and staff working at transport hubs and mail sorting offices”.
“We have shared images of the exterior packaging of two of the devices to aid staff in identifying a potentially suspicious package,” the police said.
The packages were found in the post room at Waterloo railway station, City Aviation House at City airport and the Compass Centre on the grounds of Heathrow on Tuesday.
All the packages were A4-sized white postal bags containing yellow Jiffy bags and appeared capable of igniting a small fire when opened, the Metropolitan Police said.
Widely reported images, which have not yet been verified by police, appeared to show the partially burned package destined for The Compass Centre at Heathrow, and another sent to Waterloo.
The stamps appeared to be ones issued by the Irish postal service for Valentine’s Day 2018, featuring a heart motif and the words “Love Eire N”.
Both senders’ addresses were given as Dublin, with the one addressed to Waterloo appearing to add Bus Eireann.
The bus and coach operator said police had not been in touch, with a spokeswoman saying: “Bus Eireann are currently not aware of this and we have no further comment.”
However Ireland’s main police force confirmed it was assisting the Met with its probe.
The Met Police said officers are treating the incidents as linked and are keeping an open mind regarding motives.
No-one has been injured in the three incidents and no arrests have been made.