Defence Secretary Sir Michael Fallon has refused to rule out cuts amid claims of a funding shortfall in the armed forces.
The Ministry of Defence is facing a £10 billion funding shortfall over the next decade, and plans to reduce the number of marines include removing the frontline role of one of its three commando units, according to The Times.
The Conservative Cabinet minister said the report "wasn't quite accurate" but has repeatedly sidestepped questions over cuts.
On BBC Radio 4's Today programme he refused to deny there would be cuts to the numbers.
Speaking to ITV News, he said the defence budget was the fifth biggest in the world but like any other big organisation "we're always having to look at efficiencies".
Mr Fallon said: "We're always having to look at ways of doing things better. If there are buildings we no longer need, we can sell them off, we can sell off airfields we don't use for new housing because all of that can be reinvested in the equipment we need."