The company said the measure was a response to feedback from postmen and postwomen, though the postal workers’ union said it opposed the move.
In a service update, Royal Mail said it would continue to provide its letter delivery service from Monday to Friday as normal during the COVID-19 pandemic, adding that customers “should continue to post both letters and parcels as usual on Saturday”.
It also pledged to continue collecting all mail from businesses, post offices and post boxes as usual.
Shane O’Riordain, managing director of marketing, regulation and corporate affairs at Royal Mail, said: “Our postmen and postwomen are working very hard across the UK in challenging conditions.
“As we said at the start of the coronavirus crisis, there will be some disruption to services.
“We understand the importance of the postal service in keeping the UK connected at this time.
“We have also listened to our hard-working colleagues who have asked us to ease the additional burden on them if possible. As a result, we are making some temporary changes to postal services.”
It said this had been done in consultation with the government and postal regulator Ofcom.
But the Communication Workers’ Union (CWU), which remains in dispute with the company on a series of issues relating to job security and modernisation plans, responded by saying: “We will be seeking urgent discussions with the government on this issue.
“The reduction of the Universal Service Obligation was a key factor in our live national strike ballot.
“The last thing we want to do is call strike action at this point but we will not sit back and see our members’ jobs put at threat and the service to the public worsened.”
The union had previously called for household deliveries to be cut to three days a week but on a one-day off, one-day on basis, rather than being cut over the weekend.