Higher crude oil prices and  stronger global oil demand will see Opec's earnings from oil  exports increase by nearly a third this year and keep rising  through 2011, the US Energy Department said on Tuesday.

The US Energy Information Administration, the  department's forecasting arm, raised its estimate for Opec's  2010 oil export earnings to $750 billion, up 32 percent from  $571 billion last year.

Saudi Arabia, the world's biggest oil producer, is  expected to account for one fourth of Opec's total oil export  earnings.

Expensive oil, which reached a 26-month high of almost $91  a barrel on Tuesday, has benefited Opec but hurt consumers at  the gasoline pump.

The average price of US gasoline reached $2.96 a gallon  on Monday, the most expensive pump price since October 2008,  and could hit $3 nationally by the end of this week. The price  of crude oil accounts for more than half the cost of making  gasoline.

Opec's oil export earnings are forecast to rise another 13  percent in 2011 to $847 billion, the EIA said. That would still be far from 2008's record of $966 billion  for the producer group when oil was trading at a record $147 a  barrel and U.S. gasoline soared to $4.11 a gallon that summer.

The EIA's earnings estimate comes ahead of Opec's December 11  meeting in Ecuador.

The agency said in its new monthly energy forecast  released on Tuesday that Opec's crude oil production will  increase by 400,000 barrels per day during 2011 "to  accommodate increasing world oil consumption". The EIA expects  global oil demand to grow by 1.4 million barrels per day next  year.

Opec's surplus oil production capacity should remain at  close to 5 million bpd, compared with 4.3 million bpd in 2009  and 1.5 million bpd in 2008, the EIA said. - Reuters