The Defence Secretary, Sir Michael Fallon, has told Forces News that no decisions have yet been made to reports that the Royal Navy may retire the two warships from which it can land Royal Marines on beaches.
His remarks follow claims on the BBC's Newsnight that the two amphibious assault ships, HMS Albion and HMS Bulwark, taken out of service in a new round of cuts to the Armed Forces.
It said such a move, which the Ministry of Defence (MoD) described as "pure speculation", would save money and free up crew for the two new aircraft carriers, HMS Queen Elizabeth and HMS Prince of Wales.
It comes days after Defence Secretary Sir Michael Fallon used a speech at the Conservative Party Conference to call for an increase in defence funding as his ministry announced a £1 billion support package for the Royal Navy fleet.
He said the Armed Forces must "modernise" the way it worked "as we grow our defence budget" and that as threats "intensify", his department was "now looking right across government to make sure we are doing enough, spending enough, to properly protect our country against all of those threats - cyber, hybrid warfare, rogue states, terrorist attacks":
"Spending 2% of GDP on defence is the minimum NATO commitment. We meet it but we should always aim to do better still."
Newsnight reported that the plan, coupled with the loss of 1,000 Royal Marines, had alarmed senior commando officers.
If confirmed, the loss of Albion, a former flagship of the Royal Navy, and Bulwark would leave the Navy without a dedicated amphibious assault ship.
HMS Bulwark was involved in rescuing a number of migrants from the Mediterranean last summer. Forces News was onboard:
In April, it was announced that the Royal Marines would lose 200 posts as the Royal Navy "repurposed" its staff.
Beach landings in countries and areas where the enemy controls the harbours have been used in many modern conflicts, including D-Day during the Second World War and the Falklands War.
Former Lib Dem Leader and Royal Marine, Paddy Ashdown said:
"This is not yet a decision but it soon could be, if the government is allowed to get away with cuts which would betray the best traditions of our past and damage our ability to defend ourselves in the future.
"It is time for those who value Britain's contribution, both nationally and internationally, to the preservation of peace to make sure this disastrous decision is never allowed to be taken."
An MoD spokesman said: "In the face of ever-changing threats, we are contributing to the cross-government review of national security capabilities and looking at how we best spend our rising defence budget to support that.
"No decisions have yet been made and at this stage, any discussion of the options is pure speculation."