The UK Royal Navy is planning to cut £1.5bn ($2.3bn) a year from its budget.
Under the proposed cuts, the navy will close its Devonport dockyard, retire nine older frigates and destroyers and scrap upgrades to 35 Sea King amphibious assault helicopters.
In addition, the £700m ($1bn) replacement for the amphibious carrier HMS Ocean will not be built and one of the new aircraft carriers will act as a floating base for the Royal Marines, according to the Plymouth Herald.
Plymouth Moor View Labour MP Alison Seabeck said closing Devonport would weaken national security in the long term.
"We are putting the UK at risk. We are an island, we need a navy and we need three naval bases," she said.
The £5bn ($7.7bn) construction of two new aircraft carriers, however, would go ahead but the number of jets that operate from them would be reduced.