(Updates with ANA CEO comments, JAL results)

TOKYO, Oct 31 (Reuters) - ANA Holdings said on Tuesday its first-half operating profit had more than quadrupled amid the post-pandemic travel boom but kept its full-year forecast unchanged citing higher oil prices and costs related to inspections of Pratt & Whitney engines.

Japan's largest airline plans to cut about 30 domestic and international flights a day between January 10 and March 30 as it conducts inspections of P&W's engines installed on its 33 Airbus fleet.

The cost related to the inspections would cut the company's operating profit by about 40 billion yen ($266.3 million) this fiscal year, ANA's CEO Koji Shibata told reporters.

"Passenger demand for the latter half of this year seems solid. We've kept the outlook unchanged today but I think we can aim higher."

The 140 billion yen operating profit the company expects for the current business year to March is below the mean 163.2 billion yen profit estimated by 14 analysts, according to LSEG data. Group revenue is expected to increase 15.4% to hit 1.97 trillion yen, ANA said.

In the six months to September, ANA reported a group operating profit of 129.7 billion yen against the 31.4 billion yen profit a year earlier, thanks to a weaker yen which helped lure inbound travellers.

The weaker yen, however, is sapping domestic passengers' appetite for international travel, with Japanese passengers only accounting for 35% of international flights currently - down from 49% before the COVID-19 pandemic, Shibata said.

ANA's rival Japan Airlines lifted its annual net profit forecast to 80 billion yen from 55 billion yen it had projected previously.

JAL logged a net profit of 61.7 billion yen in the six months to September, swinging to a profit after reporting a 2.2 billion yen loss a year ago. ($1 = 150.2200 yen) (Reporting by Mariko Katsumura; Editing by David Dolan and Muralikumar Anantharaman)