UPDATE 1-ANA weighs buying 30 Mitsubishi regional jets-Jiji

(Updates with background, company comments, stock prices)

TOKYO Jan 9 (Reuters) - All Nippon Airways (9202.T) and some affiliated airlines are looking at buying about 30 regional jets made by Mitsubishi Heavy Industries (7011.T), Jiji news agency reported on Wednesday.

Mitsubishi Heavy has said it aims to sell 1,000 regional passenger jets over the next 20 to 30 years, grabbing one-fifth of expected new demand in a market dominated by Canada's Bombardier Inc (BBDb.TO) and Brazil's Embraer (EMBR3.SA) (ERJ.N).

ANA spokesman Toshiki Yamamoto said the airline was studying possible jet purchases from various perspectives such as cost and capacity, but nothing had been decided.

ANA currently only operates regional jets made by Bombardier.

Mitsubishi Heavy spokesman Hideo Ikuno declined to comment.

Overall, Mitsubishi Heavy plans to spend about 150 billion yen ($1.4 billion) on the project, dubbed Mitsubishi Regional Jet (MRJ), which will seat 70 to 90 passengers.

It will make a final decision on the launch this spring and hopes to start operating the jets in 2012.

Jiji said Mitsubishi Heavy, Japan's biggest heavy machinery maker, needs to secure orders for 350 jets for the project to be viable.

The report sent Mitsubishi Heavy shares up to close 3.6 percent higher at 459 yen, extending earlier gains, while ANA shed 0.7 percent to 413 yen. The benchmark Nikkei average .N225 ended the day up 0.5 percent.

Mitsubishi Heavy announced in October it had picked U.S. firm Pratt & Whitney, a unit of United Technologies Corp (UTX.N), to supply engines for the new regional passenger jet.

Mitsubishi's new jet, which will be the first regional jet to adopt composite materials for its airframe on significant scale, is part of a larger effort by Japan to develop aircraft that are quieter and more fuel-efficient. (Reporting by Aiko Hayashi and Edwina Gibbs; Editing by Mike Miller)