Mail has been stolen from a post box in a York street and later found opened and discarded near a railway bridge.

Royal Mail customers in the Holgate area of York believe that a particular red letterbox is being overfilled, presenting an opportunity for thieves to reach in and steal the mail. The Post Office has now said it will “monitor usage” of the red pillar box, in Holgate, following the incident.

Former York councillor Liz Edge said her own mail was returned to her by a passer-by, who had found an envelope, addressed to her, discarded near the iron railway bridge in Holgate on Saturday.

The letter was one of a batch posted by Holgate-based insurance broker Perry Marshall on Friday, in the post box close to their office.

Ian Braid, Perry Marshall owner, said: “We have an issue with some of our post being discovered tampered with just after it’s been put in the post box.

“It was obvious someone had gone through it to see if there was anything valuable in it.” He called on the Post Office to carry out more collections and said some of the information in the mail-outs was “highly personal”.

Mrs Edge said the person who delivered her letter had found it with a pile of others near the bridge. “Somebody has gone to the post box and taken the letters out,” she said.

A Royal Mail spokeswoman said: “We are investigating the complaints and looking at the use of the post box. Any customers who have a query regarding Royal Mail services can contact our Customer Services team on 08457 740 740 in order that we can investigate fully.”