SINGAPORE (AFP) - Oil prices extended losses in Asia on Tuesday after leading global producer Saudi Arabia slashed its export prices for the US market while hiking them for Asian buyers.

US benchmark West Texas Intermediate (WTI) for December delivery fell 40 US cents to US$78.38 in mid-morning trade, below its lowest settlement point since June 2012.

Brent crude for December was down 38 US cents at US$84.40.

WTI dropped US$1.76 in late New York trade Monday while Brent plunged US$1.08 in London.

"Oil prices suffered another body blow... after it was reported that Saudi Arabia cut its selling price to the US possibly in a bid to compete with US shale oil," United Overseas Bank said in a commentary.

Dow Jones Newswires said Monday that Riyadh had lowered its December prices for oil shipped to the United States, where its market share has been hit hard by the rise in domestic production from shale deposits.

Saudi Arabia raised the prices for its oil in other locations, including Asia, where the country has cut its prices for four straight months, Dow Jones Newswires reported.

The move by Saudi Arabia comes ahead of a key production meeting of the Organisation of the Petroleum Exporting Countries (OPEC) on Nov 27 in Vienna.

The cartel is expected to deliberate on whether to trim its current 30 million barrels per day output to prop up prices.

Saudi Arabia, long the world's key producer, has wrestled with its options of cutting output to shore up prices or reducing prices to defend its market share.