Japan Air System Co. will extend its frequent flier program to customers of Mitsui Home Co. starting Sept. 1, the two firms jointly announced Wednesday.

Under the new program, those who sign contracts with the housing maker after Sept. 1 to build or remodel are eligible to earn mileage under the carrier's frequent flier program, they said. "As part of the sales promotion campaign, we hope to cover 1.4 million of the JAS (frequent flier program) members," said Shun Fusegawa, managing director of Mitsui Home Co.

Those who order a house from Mitsui Home costing more than 10 million yen and less than 20 million yen will be awarded 10,000 miles on their JAS programs. In addition, the miles can be counted as earned mileage toward free plane tickets from Northwest Airlines Inc. and KLM Royal Dutch Airlines -- JAS's business partners.

For housing contracts over 20 million yen but less than 30 million yen, an applicant can get 20,000 miles. Similarly, those who contract for more than 30 million yen will get 30,000 miles.

In a special campaign, JAS will will double the number of miles awarded and offer an additional 5,000 miles to Mitsui Home customers who sign contracts and actually move in between Sept. 1 and March 31, 1999.