The 248-metre long carrier would be the first Japanese vessels capable of launching warplanes since the Second World War, marking a continuation in Japan’s recent militarisation.
Following its defeat at the end of the Second World War Japan signed a deal promising not to build any offensive weapons and to convert its military into a defensive force.
Now Japan’s navy, known as the Maritime Self Defence Force, has drawn warnings from China after appearing to be moving away from the peace agreement.
Chinese foreign ministry spokesman Hua Chunying said: “We urge Japan to do more that may help enhance mutual trust and promote regional peace and stability.”
China has warned the move may violate Japan’s constitutional “no-war” clause.
Prime Minister Shinzo Abe has already drawn criticism after signing arms deals including one with the US to buy 42 F-35A.
The F-35A needs a runway and would be unsuitable for a converted Izumo-class carrier, however, it has been suggested that the order could be altered to include F-35Bs which are capable of vertical take off.
Local media has put the price of conversion at £372million ($500million) a figure which would rocket to £3billion ($4billion) if a similar ship, the Kaga, was added.
It is expected that the carrier would patrol disputed areas of the East China Sea where China and Japan both claim sovereignty over the Senkaku Islands.
The expansion comes after it was revealed Japan is building missile batteries on an island near China.
The move is part of a military expansion that will see anti-ship and anti-aircraft cruise missile batteries joined by troop garrisons and radar installations installed on Japanese islands.
The fortification comes as Beijing has aggressively sought to extend its power in the South China Sea to wrestle control of shipping lanes and islands from other nations.
Ishigaki island mayor Yoshitaka Nakayama said: “Until China becomes a country with a normal political system, we need to protect ourselves.”
However preparations were met by protests from some residents of the island who fear the move will make them a target for China’s huge military.
Anti-base activist Shizuo Ota said: “We’d be wiped out in an instant.”
Defence Minister Itsunori Onodera confirmed the missiles were needed to protect the island from invasion.