A First Class stamp will go up by 15p to £1.10 from 3 April, an increase of just under 15.8%.

Second Class stamp are going up by 10.3%, from 68p to 75p.

Royal Mail said the increases were necessary “to ensure the one-price-goes-anywhere Universal Service remains sustainable”.

It cited the ongoing decline in letter volumes to around 8bn letter per year – down 60% over the past two decades – and also significantly down on pre-pandemic volumes. 

The group also pointed to the growing number of UK addresses, which have increased by 4m to around 31m during the same period, resulting in extra costs for Royal Mail.

Chief commercial officer Nick Landon commented: “We appreciate that many businesses and households are facing a challenging economic environment and we are committed to keeping our prices affordable. 

“Letters have declined by 25% compared to pre-pandemic. We have to carefully balance our pricing against a continued decline in letter volumes and the increasing costs of delivering letters six days a week to an ever-growing number of addresses across the country.

Landon said the shift in demand from letters to parcels had resulted in a fundamental change in consumer needs.  

“It is vital that the Universal Service adapts and stays both relevant and sustainable. We need to make these price changes to ensure we can continue to maintain and invest in the one-price-goes-anywhere Universal Service for years to come.”

Royal Mail has asked the government to reduce the USO from six days a week to five for letters, which would mean scrapping Saturday deliveries. 

However, at a Westminster Hall debate regarding Royal Mail and the USO held in January, Kevin Hollinrake, the parliamentary under-secretary of state for Business, Energy & Industrial Strategy, stated: “To be completely clear, the government currently have no plans to change the statutory minimum requirements of the universal postal service, which are set out in the Postal Services Act 2011.”

Royal Mail also calculated the median equivalent First Class price across 29 European countries at the beginning of the year, and said its increased prices remained “competitive” with the resulting figure of £1.25.

Separately, a fresh move has been made to resolve the damaging ongoing dispute between Royal Mail and union the CWU. 

Senior leadership at the two parties have agreed to enter into new talks facilitated by former TUC general secretary and ACAS chair Brendan Barber. 

ACAS chief conciliator Marina Glasgow will support Barber, while Royal Mail non-executive directors Maria da Cunha and Shashi Verma “will support the talks process and provide board oversight”.

A programme of workstreams has already begun covering all of the issues in the long-running dispute. This process is set to conclude on Sunday 12  March “to secure an agreement”.

Union members voted overwhelmingly in favour of further industrial action last month.

Royal Mail expects to report an adjusted operating loss of between £350m-£450m in its current financial year.