The number of days Royal Mail delivers post could be reduced to five or even three days a week among new cost-cutting plans.

Reducing the number of delivery days is among the options being put forward for the Royal Mail by the industry watchdog as it warned the universal postal service risks becoming “unsustainable” without reform.

Ofcom said Britain’s universal postal service “must modernise” as it outlined proposals for its overhaul following a review amid calls from Royal Mail to ditch Saturday letter deliveries due to slumping demand.

It said two main options being mooted, cutting the six-day a week service to five days or three, although this would need Government and Parliament to change current laws, with another proposal being to overhaul first and second class and business services.

Chester and District Standard:

This could see the introduction of a service where most deliveries take up to three days or longer, with a next-day service still available for any urgent letters.

Ofcom said Royal Mail could make cost savings of £100 million to £200 million if letter deliveries were reduced to five days; and £400 million to £650 million if reduced to three days.

Its savings could be up to £650 million it the large majority of letters were delivered within three days.

It stressed that downgrading Royal Mail’s delivery targets “was not an option”.

Ofcom said it wanted a “national debate” on the future of the UK’s postal service, given that the number of letters being posted has halved since 2011.

Ofcom chief executive Dame Melanie Dawes said: “Postal workers are part of the fabric of our society and are critical to communities up and down the country.

“But we’re sending half as many letters as we did in 2011, and receiving many more parcels.

“The universal service hasn’t changed since then, it’s getting out of date and will become unsustainable if we don’t take action.

“So we’ve set out options for reform so there can be a national discussion about the future of universal post.

“In the meantime, we’re making sure prices will remain affordable by capping the price of second class stamps.”

When does the Royal Mail deliver post in the UK?

The Royal Mail delivers post from Monday to Saturday each week with no deliveries being made on Sunday. This excludes bank holidays.

Letters to Europe are delivered within three to five days of being dispatched by the postal service.

Letters sent anywhere else in the world take five to seven days to be delivered.

Does Royal Mail deliver after 5pm?

According to the PostGrid website, the Royal Mail can make deliveries after 5pm if the service is running a bit late.

They said: "Royal Mail does not officially deliver after 6 p.m. Yet, you can expect deliveries in the evening if the courier service is running later on schedule."

However, in most cases, deliveries will stop at 5pm as the service will be running on schedule.

Citizens Advice adds: "Your post should be delivered by 3pm if you live in a town or city, or 4pm if you live in a rural area.

"You can check if post will be delayed in your local area on the Royal Mail website."