Japan is reportedly planning to sell Kawasaki P-1 submarine-hunting patrol planes to the UK.
The planes could replace the UK Royal Air Force's Nimrod jets and would be Japan's first major military deal outside the Asia-Pacific region, if finalised.
Any possible deal could reach $1bn and would be a major step forward in Japanese Prime Minister Shinzo Abe's initiative to export arms after decades of self-imposed restrictions, Reuters reported.
A UK Ministry of Defence spokesperson was quoted by media sources as saying: "We will continue to assess future requirements ahead of a decision in the next strategic defence and security review in 2015."
An undisclosed Japanese source said: "If the UK gives it serious consideration, then the P-1 will garner attention internationally."
However, the UK has not confirmed its plans regarding the procurement of maritime patrol planes, having abandoned an order for nine BAE Systems-built aircraft in 2010 because of delays and rising costs.
Kawasaki Heavy spokesperson Teppei Kobayashi said: "We are not aware of the discussion so we can't comment.
"In general, it is a matter of national policy, so if there is a decision that results in an order, we will follow that."
Since the lifting of restrictions on military exports in April, the Japanese Defence Ministry has been considering deals to sell submarines to Australia and sea jets to India.