TOKYO MUFG Bank is among three Japanese firms leading a $290-million fundraising round for U.S. spaceship company Sierra Space, spearheading a commercial "spaceport" project in the southwestern region of Oita, the Nikkei daily said on Tuesday.

Despite recent setbacks for national space missions, Japanese companies aiming to foray into space are increasingly deepening ties with private companies, from American giants such as SpaceX to home-grown startups.

MUFG Bank, insurer Tokio Marine & Nichido Fire and trading house Kanematsu together invested several tens of billions of yen in Sierra, gaining a stake in the unlisted company that was now probably valued in excess of $5 billion, the paper said.

A spokesperson of Tokio Marine & Nichido Fire, a unit of Tokio Marine Holdings, confirmed that the three companies formed a strategic partnership with Sierra, but declined to elaborate on their investments.

Spokespersons for Mitsubishi UFJ Financial Group's MUFG Bank and Kanematsu Corp declined to comment.

Earlier, CNBC said the deal included "significant participation from prior investors and insiders" of Sierra, in addition to the Japanese firms.

Sierra Space, spun off in 20221 from billionaire-owned Sierra Nevada Corp, is among a handful of space industry players attempting to build a private space station that NASA hopes will replace the two decade-old International Space Station by 2030.

Sierra signed a partnership in December with Kanematsu, Japan Airlines and the Oita prefectural government to turn a regional airport into Asia's first "horizontal spaceport".

The Oita project took a hit this year from the bankruptcy of another U.S. space company Virgin Orbit, which had partnered with airline ANA Holdings.

MUFG Bank, one of Japan's three biggest, has invested in domestic space startups such as orbital debris-removal firm Astroscale.

Tokio Marine's rival Mitsui Sumitomo Insurance said it provided the world's first "lunar insurance" to ispace inc's moon landing mission, which failed in April.

The vigorous commercial projects stand in contrast with the Japan Aerospace Exploration Agency's (JAXA) unsuccessful space missions since last year.

But its SLIM lander launched this month would make Japan the fifth in the world to put a spacecraft on the moon if the early 2024 mission succeeds.

($1=148.8700 yen)

(Reporting by Kantaro Komiya; Editing by Clarence Fernandez)