Three of five major Japanese oil refiners slipped into the red in the six months ended September and two of them are curbing investments as the slump in oil prices, which shows little sign of ending, caused inventory losses.

Worldwide, top oil companies have struggled to cope with the halving of oil prices since June 2014. They have slashed spending, made thousands of job cuts and scrapped projects.

JX Holdings, Idemitsu Kosan and Cosmo Energy Holdings reported losses in the six months ended September, erasing profits posted in April-June quarter.

Top refiner JX Holdings, which reported net loss of 44.95 billion yen ($370 million) in the first half, has curbed its 1.3 trillion yen ($10.70 billion) three-year investment plan ending next March by 1.5 per cent.

Taking into account a significant weakening of the Japanese yen that pushed up the value of overseas investments, the lower target is equal to cutting spending by nearly 100 billion yen, JX Holdings director Katsuyuki Ota told reporters. JX lowered its full-year net profit outlook to 45 billion yen from 160 billion yen, saddled with 80 billion yen of inventory losses. That fell below the Thomson Reuters mean estimate of 114.46 billion yen of eight analysts.

JX Holdings has also increased cost cutting targets by a third from the earlier planned 30 billion yen, and is planning to sell some of its stakes in overseas upstream projects and share holdings in listed firms to create 200 billion yen worth of cash flow over two years ending next March, Ota added.