Former Royal Navy flagship HMS Ark Royal will be sold on as scrap metal for £3 million as part of a move that the Ministry of Defence has described as "difficult but necessary".

An announcement in Parliament tomorrow is expected to reveal the details of the deal after the vessel was decommissioned in 2010 five years ahead of its expected sell-by date.

The decision comes following a bidding process which included proposals to turn the 22,000-ton ship into a helipad in the Thames, a museum, a hotel, a casino or a diving wreck off the South coast.

Last year HMS Invincible was also sold to a Turkish scrap metal firm as part of the MoD's drive to get its finances in order.

But HMS Illustrious, commissioned in June 1982 just days after the Falklands War, is expected to be preserved after completing active service as a helicopter carrier in 2014, according to The Sun on Sunday. 

A MoD spokesman said: "HMS Ark Royal was decommissioned in 2010 after three decades of service and an announcement on her future will be made to Parliament on Monday.

"Retiring her five years earlier than planned was a difficult but necessary decision to help address the multi-billion pound Defence deficit and deliver a balanced MoD budget.

"The new, much larger Queen Elizabeth aircraft carriers will start to enter service in 2017."

Ark Royal is seen as a symbol of the former might and current woes of the Royal Navy, being the fifth vessel to carry the name of the flagship which saw off the Spanish Armada in 1588.

Known as the Mighty Ark, the light aircraft carrier saw action in the Adriatic during the Bosnian War in 1993 before being sent to lead the British fleet during the invasion of Iraq a decade later.

Following the Defence and Security Review's decision to scupper the vessel and ground the Navy's Harrier jump jet fleet 18 months ago, the Royal Ark has been awaiting its fate in Portsmouth harbour.