Japan's Mitsubishi Motors is set to join an alliance between Honda Motor and Nissan Motor, creating an auto group with combined sales of more than 8 million vehicles, the Nikkei business daily said.

Mitsubishi Motors, which is 34% owned by Nissan, will work with Honda and Nissan to finalise the details of their partnership, but the three firms intend to standardise in-vehicle software that controls cars, Nikkei said on Sunday.

Mitsubishi Motors declined to comment on the report, while officials at Nissan and Honda were not immediately available for comment.

The push comes as Nissan, Japan's third biggest automaker, has been steadily losing market share in its two largest markets, the United States and China, which together accounted for half of its global sales in the year to March.

On Thursday, the company slashed its annual outlook after heavy discounting in the US almost completely wiped out its first-quarter profit.

Collaboration could help Japan's automakers cut costs and beef up to battle tough competition in electric vehicles, dominated by companies like China's BYD and Tesla .

In China, the world's largest auto market, Japanese brands previously were strong but are now up against domestic automakers that have rapidly increased production and won over consumers with low-priced vehicles loaded with software.

Nissan and Honda said in March they were considering a strategic partnership on producing EV components as they seek to gain a greater foothold in the global market for battery-powered cars, which is expected to grow over the coming years.