* OPEC supply falls by 280,000 bpd to 32.37 million bpd
* Iraq posts largest decline due to northern export halt
* Saudi Arabia keeps output flat, following freeze deal
* Iran increases supply, but not as fast as it says
* For a table of OPEC output, see
By Alex Lawler
LONDON, Feb 29 (Reuters) - OPEC oil output has fallen inFebruary from the highest monthly level in recent history, aReuters survey found on Monday, due to a halt in Iraq's northernexports and outages in other producers.
The survey also found stable output in top exporter SaudiArabia, an early sign that Riyadh is delivering on a Feb. 16deal along with Venezuela, Qatar and non-member Russia to freezeoutput and support prices, which hit a 12-year low last month.
Supply from the Organization of the Petroleum ExportingCountries has declined in February to 32.37 million barrels perday (bpd) from a revised 32.65 million bpd in January, accordingto the survey, based on shipping data and information fromsources at oil companies, OPEC and consultants.
Most of the decline in February output has been involuntary.The biggest drop is in Iraq, OPEC's largest source of supplygrowth in 2015, due to the stoppage in flow along the pipelinecarrying crude from the Kurdish region.
"The interruption from Kurdistan is significant because theywere a big part of the increase in exports from Iraq," saidOlivier Jakob, analyst at Petromatrix. "It is prompt suppliesand these are large volumes."
The pipeline, which had been carrying around 600,000 bpd inrecent months, has been offline since Feb. 17 and could be shutuntil mid-March.
Production also declined in Nigeria, where Royal DutchShell's Nigerian venture suspended the flow of Forcadoscrude to the export terminal following a spill. The incidentadded to the impact of lower scheduled exports.
Field maintenance including at the Murban development hasreduced output in the United Arab Emirates, the survey found.
Saudi Arabia has kept output steady compared with January at10.20 million bpd, sources in the survey said, citing stableexports in much of February. Saudi production reached a recordhigh of 10.56 million bpd in June.
Of the countries increasing output, Iran boosted supplyfurther following the lifting of Western sanctions in January.Iran, which wants to recover market share it lost undersanctions, has criticised the production freeze agreement.
Iran has increased supply by 200,000 bpd since December,according to Reuters surveys, while Iranian officials say thecountry has boosted exports by a much larger 500,000 bpd.
OPEC production has surged since the group in November 2014abandoned its traditional role of cutting supply alone to propup prices, in the hope that lower prices would curb the growthof more costly-to-develop competing supply sources.
The extra OPEC barrels have helped to create one of thebiggest supply gluts in history, and the production freezeagreed by the three OPEC members plus Russia represents thefirst global production pact since 2001. (Editing by Dale Hudson)