ROYAL Mail could switch to a three-day-a week service in a major shake-up according to Ofcom.
The regulator said cutting letter deliveries to five or three days are among options that could be considered despite fury over the cuts.
Ofcom warned the universal postal service risks becoming “unsustainable” without reform.
Cutting down to five days would mean savings of £100 million to £200 million.
Meanwhile, three days would see expected savings of £400-600 million.
It comes as Downing Street vowed that Royal Mail will not be allowed to scrap Saturday post deliveries.
Number 10 said the Government “would not countenance” ending the six-days a week service after speculation swirled over the weekend about possible cuts.
The Prime Minister’s spokesman said: “The PM’s strong view is that Saturday deliveries provide flexibility and convenience.
“They are important for businesses and particularly publishers. The Prime Minister would not countenance seeing Saturday deliveries scrapped.”
Postal Service Minister Kevin Hollinrake also told The Sun: “Six-day week deliveries are very important to our constituents and to many businesses, particularly in the magazine and greeting cards industries.