OPEC output fell in February from a two-year high the previous month as the uprising in Libya curbed supplies from Africa's third-largest producer, even as Saudi Arabia pumped more, a Reuters survey showed on Tuesday.

The loss of a large part of Libya's high-quality oil has sent oil prices well over $100 a barrel and leaves a difficult hole for the Organization of the Petroleum Exporting Countries to fill on world markets.

Supply from all 12 members of OPEC averaged 29.43 million barrels per day (bpd) in February, down from a revised 29.63 million bpd in January, the survey of oil companies, OPEC officials and analysts found.

Libya's production posted the largest decline of 230,000 bpd as workers left oilfields because of the turmoil in the country. Output had been running at a normal rate near 1.6 million bpd for much of February.

Almost half of the production went down, Shokri Ghanem, the head of Libya's National Oil Corporation, said in an interview with Reuters. Some fields are still producing at capacity. Some are closed. It depends on the labor.

The Libyan crisis has, for now, halted a steady rise in supply from OPEC in response to recovering world demand and higher oil prices, which last week neared $120 a barrel for the first time since 2008.

Output also fell in February in Iraq, which did not sustain a surge in exports for a second month, and declined in Nigeria -- like Libya a producer of high-quality oil -- because of field maintenance, the survey showed.

Higher supplies in January from Iraq, which is not bound by the OPEC output limits that the other 11 members agree to, helped send OPEC output to its highest since December 2008.

QUALITY AND QUANTITY ISSUES

Saudi Arabia lifted supply to 8.65 million bpd during February and supply by the end of the month was up to 9 million bpd, the survey found.

The kingdom promised last week that it would meet any supply gap caused by unrest in Libya and industry surveys showed it was already raising supply to meet higher demand. Output in January was revised up to 8.5 million bpd.

While Riyadh is in theory able to replace the quantity of Libyan output lost completely, analysts doubt extra Saudi barrels will be of the same quality as Libya's. The loss of high-quality oil on Europe's doorstep is one of the reasons for the jump in oil prices.

OPEC needs to fill both a quality and quantity gap left by Libya, said Harry Tchilinguirian, head of commodity markets strategy at BNP Paribas. Although Saudi Arabia has indicated it can supply more Arab Extra Light, there is no indication to date that it has.

Among other OPEC countries boosting output in February, Iranian production climbed because the country sold some of the oil it had been storing in tankers.

OPEC has not officially changed its policy for more than two years since cutting output by a record 4.2 million bpd in December 2008 as prices fell and recession destroyed demand.

In the months following the agreement, OPEC completed as much as 80 percent of the supply reduction but production has been rising since mid-2009 in response to a recovery in world demand and higher prices.

OPEC does not provide timely official figures for its production, so the oil industry relies on estimates provided by news agencies, consulting firms and organizations such as the International Energy Agency for estimates of its supply.

(Editing by Jason Neely)

Nigeria Iraq Libya BNP Paribas