LONDON: Oil prices were narrowly mixed on Tuesday amid concerns over large stockpiles in the United States caused by weak demand in the world's biggest consumer, traders said.

The OPEC oil producers' cartel on Tuesday upgraded slightly its forecast for world oil demand growth next year but said usage in advanced economies would contract again.

Brent North Sea crude for delivery in January dipped 12 cents to 71.77 dollars a barrel in midday London trading.

New York's main contract, light sweet crude for January, edged up four cents to 69.55 dollars.

Relatively high oil stocks have renewed concerns over weak energy demand in the United States, a nation struggling to mount a strong recovery from its deep recession.

"Demand concerns are still present," VTB Capital commodities analyst Andrey Kryuchenkov said on Tuesday.

World oil demand is meanwhile "forecast to return to growth in 2010 following two years of devastating declines," the Organization of Petroleum Exporting Countries (OPEC) said in its December report.

It said demand would grow by 0.82 million barrels per day (bpd) or 0.9 percent to average 85.13 million bpd, up slightly from its previous forecast for an increase of 0.75 million bpd.

But growth would be driven by developing countries, with demand in industrialised or OECD (Organisation for Economic Co-operation and Development) nations continuing to contract, the cartel said.

OECD oil demand was set to contract 0.28 percent in 2010 after falling by a record 3.9 percent in 2009.

Last year was "one of the worst years," with global demand estimated to have contracted by 1.39 million bpd or 1.6 percent to 84.31 million bpd, OPEC said.

The cartel is set to hold a meeting to discuss output on December 22 in the Angolan capital Luanda.

New York oil prices on Monday lost ground for a ninth session amid persistent fears that supply is outpacing demand.

The trend in oil prices suggests that the global economy, although coming out of recession, may not be robust enough to support increased energy demand while supplies are increasing.

"Oil is still being held back by a load of supply," said Phil Flynn at PFG Best Research.