LONDON- Saudi Arabia has yet to brief fellow OPEC members and other energy sector players about how long it will take to restore the country's oil output, OPEC and industry sources said as Riyadh tries to assess damage from the weekend's crippling attacks.

Saturday's attacks on oil facilities will cut the kingdom's output by 5.7 million barrels per day, state-run producer Saudi Aramco said. Sources have said a return to normal production could take months. 

The United States has said it looked like Iran was behind the strike at the heart of the Saudi oil industry, which cut 5% of global production. Iran denied it was to blame.

The oil market is far from transparent. Information on supply outages and other events likely to affect prices often leaks informally, however, and is shared via instant messaging.

This time, that's not the case. Other members of the Organization of the Petroleum Exporting Countries are among those awaiting a news conference that the Saudi energy minister, Prince Abdulaziz bin Salman, is due to hold around 1700 GMT.

"Not at all," said an OPEC delegate from one of the group's larger producers, referring to whether he had heard any news on the outage. "We are waiting for today's press conference and hope it's not too serious an impact."

"I think they are still assessing the damage and coping with many urgent matters," another OPEC delegate said. "It is indeed a big shock. Nothing will be as before."

Russian Energy Minister Alexander Novak was in a similar position, saying on Monday there was no new information. urn:newsml:reuters.com:*:nL5N2676C9 Russia is the biggest non-member producer working with OPEC in a supply-cutting deal.

The International Energy Agency, which advises industrialised countries and manages their emergency oil stocks, was also waiting for the news conference before deciding on a course of action, two sources said.

While some Asian buyers of Saudi crude have been notified of loading delays to their cargoes, this was not yet the case in Europe, which buys less Saudi oil than Asia.

"We have no information so far," a trade source said. "There are some signals that some grades could be replaced with others, but nothing official. No force majeure or any other communication."

(Additional reporting by Ron Bousso and Vladimir Soldatkin; Editing by Dale Hudson) ((alex.lawler@thomsonreuters.com; +44 207 542 4087; Reuters Messaging: alex.lawler.reuters.com@reuters.net))