Royal Mail has defended itself against suggestions it was failing to cope with the strain on services caused by an ongoing industrial dispute.

Pictures of mail strewn across the pavement were taken by a customer who had visited a sorting office in south London to collect overdue post.

The woman, named only as Vicky, told the BBC: "I was surprised to see the mail in the street and pedestrians walking over it.

"I've only had three bits of post in the past three weeks."

The Wimbledon office was one of a number involved in strike action as part of the dispute over jobs, pay and services.

A Royal Mail spokesman said: "We are doing everything we can to get as much mail to customers as soon as possible, including using management volunteers, to lessen the impact of the CWU strike action.

"All but a handful of our 1,400 delivery offices were working today (Saturday) and the activity in the picture was exceptional and shows we are determined to get our customers mail to them."

According to the Communication Workers Union, the dispute is the biggest with Royal Mail since the national strike of 2007 and has led to a backlog of undelivered post.

Strikes have taken place at a local level since June.

Postal services are set to be hit by more walkouts next week, starting with delivery offices in Cambridgeshire on Monday.