By Osamu Tsukimori

TOKYO, Oct 19 (Reuters) - Japanese traders including Marubeni Corp and Sumitomo Corp that stopped buying Iranian oil during western sanctions are looking to resume imports, potentially by year-end, industry sources said.

Conservative Japanese firms have so far held off taking Iranian crude due to a lack of internationally acceptable insurance coverage, but are looking at ways of using cover provided by the Japanese government, the sources said.

The traders seeking to restart purchases together imported around 50,000 barrels per day (bpd) of Iranian oil before sanctions were imposed and renewed purchases would give a boost to Tehran's aim of increasing its exports to 4 million bpd.

Other Asian buyers have stepped up purchases of Iranian oil since sanctions were lifted in January, with Iranian imports to Asia, excluding Japan, jumping to 1.60 million bpd in August, up 92 percent on a year ago.

Buyers have taken advantage of a scheme put together by ship owners to plug a shortfall in insurance cover due to ongoing restrictions on U.S.-domiciled reinsurers, but Japanese firms have been reluctant to take part.

Trading houses have been waiting for private shipping insurance to return to full coverage, which could come as early as this year. But some traders now hope to piggyback on a Japanese government scheme that has been providing ongoing cover for so-called "essential" imports of Iranian oil throughout the sanctions.

The government-cover enabled refiners and trading houses such as Mitsubishi Corp 8058.T and Toyota Tsusho 8015.T to import Iranian oil even after the sanctions were imposed in 2012.

"One solution would be to co-load oil with other buyers," said a source with a trading house. Oil loaded on vessels already covered by the government scheme would also be fully insured, they said.

Earlier this month, Mitsui & Co resumed taking Iranian oil for the first time since at least 2012, co-loading Iranian condensate with a major Japanese refiner on a tanker, a source familiar with the shipping schedule said. Mitsui declined to comment.

Marubeni, which bought Iranian crude, condensate, naphtha and fuel oil until 2012, confirmed it had been working to restart purchases. A company source told Reuters it hoped to resume imports by the end of the year.

Sumitomo, which bought liquefied petroleum gas (LPG) from Iran before the sanctions, was also looking to buy Iranian oil and LPG as long as prices were competitive, an industry source close to the matter said. The company declined to comment.

Itochu Corp 8001.T said it was considering resuming imports of Iranian oil, while trading house Kanematsu Corp 8020.T which last bought Iran crude in 2010, is also looking to resume purchases at an early date, but has not yet lined up any customers, a company source told Reuters.

(Reporting by Osamu Tsukimori; Editing by Aaron Sheldrick and Richard Pullin) ((osamu.tsukimori@thomsonreuters.com, +813 6441 1857, Reuters Messaging: osamu.tsukimori.thomsonreuters.com@reuters.net;))