Royal Mail has confirmed a further widespread delay in delivery dates, after Epping Forest MP Dame Eleanor Laing called for a “rapid and significant improvement” in services.

The postal service said some areas will see a reduced service due to workers being off sick or self-isolating and listed areas including Ilford, South Woodford and Enfield as those most affected.

It comes after the Epping Forest MP was informed by the Royal Mail that 43 per cent of staff at the Debden Delivery Office, which serves the IG8 postcode area, were off work, with figures up from 40 per cent on December 11.

The senior public affairs manager, Michael Hogg, said the absences were for coronavirus-related issues, and with five staff members shielding.

He added some staff were absent for long-term sickness reasons, weekly rest days and annual holidays.

Now Royal Mail listed 28 areas most affected by the reduced service, with 27 of them being in England and one in Northern Ireland.

The areas affected are:

Ashford (TN23-TN27)

Barnsley (S70, S71, S72 and S75)

Basildon (SS13-SS16)

Bow (E3)

Bury St Edmunds (IP28-IP33)

Chelmsford (CM1-CM3)

Christchurch (BH23)

Daventry (NN11)

Debden (IG7-IG10)

Enfield (EN1-EN3)

Grays (RM16-RM20)

Hampton (TW12)

Highbury (N5)

Hornsey (N8)

Horsham (RH12, RH13)

Ilford (IG1-IG6)

Leeds City (LS1-LS5)

Lewisham (SE13)

Magherafelt (BT45, BT46)

Margate (CT7-CT9)

Rugeley (WS15)

Somerton (TA11)

South Ockendon (RM15)

South Woodford (E18)

Upper Holloway (N7)

Wandsworth (SW18)

Wellington (TA21)

Widnes (WA8)

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."

Ilford MP West Streeting tweeted on Sunday that he was concerned about vaccination invitations getting caught up in the 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.

Dame Eleanor previously said: "Obviously my best wishes go to all those staff who are off sick or having to shield however it is an unacceptable situation that so many people in the area have been without regular postal deliveries for such a long time."

She added: "When so many people are having to stay at home, it is all the more important that they can expect regular post deliveries so they can keep in touch with loved ones, and not have the worry of not receiving important items of mail such as hospital appointment dates, financial documents and bank cards.

"I have written to Royal Mail and welcome the reply that promises that the cases I have highlighted will be investigated."

The MP said she hopes for "significant" improvement.