U.S. oil and gas company ConocoPhillips is reviewing its portfolio in Indonesia and may soon seek buyers for a stake in a production sharing block it operates in the Natuna Sea, company and government sources said.

The company has proposed to upstream oil and gas regulator SKKMigas to open its data room for the South Natuna Sea Block B, the agency's spokesman Elan Biantoro told Reuters, noting that such requests were usually made by companies "that want to farm out their participating interests."

ConocoPhillips was opening the data room to offer its share to other investors, spokesman Joang Laksanto confirmed to Reuters.

ConocoPhillips holds a 40 percent interest in South Natuna Sea Block B, and other companies with participating interests are Chevron, with 25 percent, and Japan's Inpex , which holds 35 percent.

Operating two oil and gas blocks in Indonesia - Natuna and the Corridor Block in South Sumatra - ConocoPhillips contributes more than 20 percent of Indonesia's natural gas production, 24 percent of its liquefied petroleum gas output and 6-7 percent of its crude oil production, according to Indonesia's energy minister, Sudirman Said.

ConocoPhillips' contract to operate the Natuna Sea Block B is due to expire in 2028.