Brent crude fell towards $84 a barrel on Tuesday, extending losses to a fourth session after top oil exporter Saudi Arabia cut prices to the US.

The cut hammered oil prices on Monday as it underscored Saudi efforts to fight for market share in the world's largest oil consumer while raising prices to Asia and Europe.

The absence of signs that the Organization of the Petroleum Exporting Countries (Opec) could curb output in a well supplied market also continued to weigh on sentiment.

A global supply glut along with slack demand has pushed down the oil benchmark more than 27 per cent from this year's peak in June.

Front-month Brent was down 37 cents at $84.41 a barrel by 0305 GMT. Brent dropped $1.08 on Monday, its biggest daily loss in nearly two weeks.

US December crude declined 41 cents to $78.37 a barrel. It was also down for a fourth consecutive session, after hitting $78.08 on Monday, its lowest level since June 2012.

"There's just plenty of supply and production is still strong in the US, while demand is not so huge. If they still cannot export, the upside (for prices) is limited," said Ken Hasegawa, commodity sales manager of Newedge Japan.

West Texas Intermediate could fall further towards the 2012 low of $77.28 and Brent should weaken correspondingly, he said.

There is a growing lobby in the United States to lift a 40-year ban on US crude exports which if successful could ease the supply glut in the Atlantic Basin.

Hasegawa said Opec's inaction amid the deepening oil rout meant prices had yet to find a floor.

"Opec is silent on any production cuts. If they still keep this attitude, there's no clear level of support (for oil prices)," he said.

The oil cartel will meet on Nov. 27 in Vienna to discuss its oil output targets for next year.

Members Venezuela and Ecuador are working on a joint proposal to defend oil prices, but Opec's secretary general indicated the production target next year would not vary much from 2014.

The stronger dollar is also weighing on oil prices, making the commodity more expensive for buyers using other currencies. The dollar was trading near its highest in more than four years versus a basket of currencies, freshly aided by strong US manufacturing data. – Reuters