By Ron Bousso and Joshua Schneyer

LONDON/NEW YORK (Reuters) - Saudi Arabia is quietly telling the oil market it would be comfortable with much lower oil prices for an extended period, a sharp shift in policy that may be aimed at slowing the expansion of rival producers including those in the U.S. shale patch.

Some OPEC members including Venezuela are clamoring for production cuts to push oil prices back up above $100 a barrel.

But Saudi officials have given a different message in meetings with investors and analysts: the kingdom, OPEC’s largest producer, will accept oil prices below $90 per barrel, and perhaps down to $80, for as long as a year or two, according to people who have been briefed on the recent conversations.

The discussions, some in New York over the past week, offer the clearest sign yet that the kingdom is setting aside its longstanding de facto aim of holding prices at around $100 a barrel for Brent crude in favor of retaining market share in years to come.

The Saudis appear to be betting lower prices – which could strain the finances of some members of the Organization of the Petroleum Exporting Countries – will be necessary to pave the way for higher revenue in the medium term, by curbing new investment and further increases in supply from places like the U.S. shale patch or ultra-deepwater, according to the sources, who declined to be identified due to the private nature of the discussions.

The conversations with Saudi officials did not offer any specific guidance on whether - or by how much - the kingdom might agree to cut output, a move many analysts are expecting in order to shore up a global market that is producing substantially more crude than it can consume. Saudi Arabia pumps around a third of OPEC’s oil, or about 9.7 million barrels a day.

Asked about coming Saudi output curbs, one Saudi official responded "What cuts?", according to one of the sources.

Also uncertain is whether the Saudi briefings to oil market observers represent a new tack it is committed to, or a talking point meant to cajole other OPEC members to join Riyadh in eventually tightening the taps on supply.

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One source not directly involved in the discussions said the kingdom does not necessarily want prices to slide further, but is unwilling to shoulder production cuts unilaterally and is prepared to tolerate lower prices until others in OPEC commit to action.

OPEC ANGST

With most other members of the cartel unable or unwilling to reduce their own output, the group's next meeting on Nov. 27 is set to be its most difficult in years. OPEC has agreed to cut production only a handful of times in the past decade, most recently in the aftermath of the 2008 financial crisis.

On Friday, Venezuela - one of the cartel's most price-sensitive members - became the first to call openly for emergency action even earlier. Foreign Minister Rafael Ramirez said "it doesn't suit anyone to have a price war, for the price to fall below $100 a barrel".

On Sunday, Ali al-Omair, oil minister of Saudi Arabia's core Gulf ally Kuwait, appeared to be the first to articulate the emerging view of OPEC's most influential member, saying output cuts would do little to prop up prices in the face of rising production from Russia and the United States.

"I don't think today there is a chance that (OPEC) countries would reduce their production," state news agency KUNA quoted him as saying.

Omair said that prices should stop falling at around $76 to $77 a barrel, citing production costs in places such as the United States, where a shale oil boom has unexpectedly reversed dwindling output and pushed production to its highest level since the 1980s.

Saudi oil officials have made no public comments on the deepening swoon in markets. Senior officials did not reply to questions from Reuters about recent briefings.

DON'T BE SURPRISED BELOW $90

Global benchmark Brent crude oil futures have fallen steadily for almost four months, dropping 23 percent from a June high of over $115 a barrel as fears of a Mideast supply disruption ebbed, U.S. shale production boomed and demand from Europe and China showed signs of flagging. [O/R]

Brent fell below $88 a barrel on Monday, hitting its lowest in almost four years, after news of the Saudi and Kuwaiti statements.

"In light of these comments, one should not expect any OPEC output cuts before the Nov. 27 meeting," said Bjarne Schieldrop, chief commodity analyst at SEB in Oslo.

An OPEC delegate from outside the core Gulf Arab group said he did not think OPEC would cut output at the November meeting but added he believed the Saudis should cut output unilaterally:

"The question should be posed to Saudi Arabia".

The growing difference in opinions means OPEC is heading for its most tense meeting since mid-2011 when it failed to agree on an increase in output despite a loss of Libyan production.

Until recently, Gulf OPEC members have been saying that the price dip was a temporary phenomenon, betting on seasonal demand in winter to prop up prices. But a growing number of oil analysts now see the latest slide as something more than a seasonal downswing; some say it is the start of a pivotal shift to a prolonged period of relative abundance.

Rather than fight the decline in prices and cede market share in the face of growing competition, Saudi Arabia appears to be preparing traders for a sea change in prices.

The Saudis want the world to know that "nobody should be surprised” with oil under $90 a barrel, according to one of the people. Another source suggested that $80 a barrel may now be an acceptable floor for the kingdom, although several other analysts said that figure seemed too low. Brent has averaged around $103 since 2010, trading mostly between $100 and $120.

While the latest discussions are the bluntest efforts yet to signal the shift in Saudi strategy, early signs had already begun sending shivers through the oil market. In early October the kingdom cut its official selling prices more sharply than expected in a bid to maintain customers in Asia, widely seen as the opening shots in a price war for Asian customers.

"Riyadh's political floor on oil prices is weakening," Robert McNally, a White House adviser to former President George W. Bush and president of the Rapidan Group energy consultancy, wrote in a note to clients following a trip to Saudi last month.

McNally said he is not aware of any specific Saudi price or timing strategy, but told Reuters that Saudi Arabia "will accept a price decline necessary to sweat whatever supply cuts are needed to balance the market out of the U.S. shale oil sector.”

As that message began to dawn last week, the price rout quickened, with Brent lurching to its lowest level since 2010.

"Until about three days ago the absolute and total consensus in the market was the Saudis would cut," said McNally. That is no longer a foregone conclusion, he said. "The market suddenly realizes it is operating without a net."

(Additional reporting by Rania el Gamal in Dubai and Timothy Gardner in Washington; editing by Jonathan Leff, Christopher Johnson and Jason Neely)