Royal Mail has published a list of areas where there have been delivery delays due to its workforce being affected by the Covid pandemic.
The postal service said some areas will see a reduced service due to workers being off sick or self-isolating.
Royal Mail listed 28 areas where post might be late, with 27 in England and one in Northern Ireland.
Problems with deliveries over Christmas had prompted shoppers to complain about parcels not arriving on time.
Royal Mail said: “Despite our best efforts and significant investment in extra resource, some customers may experience slightly longer delivery timescales than our usual service standards.
“This is due to the exceptionally high volumes we are seeing, exacerbated by the coronavirus-related measures we have put in place in local mail centres and delivery offices to keep our people and customers safe.”
Many of the affected areas are in or near London, while others include Chelmsford in Essex, Leeds in West Yorkshire, Margate in Kent, and Widnes in Cheshire.
Labour MP Wes Streeting, whose Ilford constituency is one of the areas affected, tweeted on Sunday that he was concerned about vaccination invitations getting caught up in Royal Mail delays.
But Covid vaccine deployment minister Nadhim Zahawi replied that the government would work with Royal Mail to ensure that vaccine invitations were prioritised.
Customers have taken to Twitter to complain about delays to their postal service.
“Unfortunately I live in one of these areas.,” wrote Matt S. “N8 has been receiving an absolutely dreadful service since April 2020 – @RoyalMail what are you going to do to improve the situation?”
Mark Harrison wrote: “We could manage and expect a bit of disruption – but we’ve had only 2 deliveries in a month. Nothing for a fortnight. SE11 not even on the list of disrupted areas. Royal Mail need to get a grip.”
In a service update on Tuesday, Royal Mail said: “Due to resourcing issues, deliveries in the following areas are likely to be limited.”
The areas affected are: