Major Japanese trade houses Mitsui & Co. and Mitsubishi Corp. said Tuesday they have trimmed the value of their stakes in the Sakhalin-2 oil and natural gas project in the Russian Far East by a combined ¥217.7 billion ($1.7 billion), citing growing business uncertainty.

Mitsui cut its investment value by ¥136.6 billion and Mitsubishi by ¥81.1 billion after Russian President Vladimir Putin signed a decree in late June to seize control of the project with the creation of a new operating company.

"It's possible that the value fluctuates further depending on the situation," Mitsubishi Chief Financial Officer Yuzo Nouchi said at a news conference on its earnings for the April-June period.