Oil at ; Iran keeps market on edge

LONDON, Mar 29 (Reuters) Oil held above on Thursday, after achieving its highest close for over six months, as 15 British sailors remained in Iranian custody and oil consumers weighed the risks to oil flows from the Gulf.

Iran, the world's fourth biggest oil exporter, may delay releasing the only woman among the 15 if Britain displays ''fuss and wrong behaviour,'' a senior Iranian official said.

U.S. crude was flat at .08 a barrel by 1135 GMT, after closing above for the first time since September 11. London Brent was up 36 cents at .14.

Iran detained the British sailors and marines on Friday, shortly before the United Nations imposed new sanctions over the Islamic republic's nuclear programme. The United States has been conducting naval exercises in the Gulf.

''Tensions are increasing between the main protagonists and they will persist even if the sailors are released,'' said Olivier Jakob, an analyst at Petromatrix in Switzerland.

''The current state of tension between the U.S. and Iran makes it probable that there will be other incidents and strategic plays until the next UN sanction review in 60 days.'' Oil prices briefly spiked above late on Tuesday on rumours of a clash between U.S. or British forces and Iran. London and Washington denied any confrontation.

So far there has been no disruption to Iran's daily oil shipments of around 2.2 million barrels.

Iran borders the Strait of Hormuz, conduit for roughly two-fifths of all globally traded oil.

Edward Meir, an analyst at Man Financial, said the oil market was being driven entirely by headlines.

''As long as the situation with the British seamen remains unresolved, we don't expect to see much in the way of dramatic declines. Conversely, any announcement of an imminent release could result in a rather sharp pullback,'' he said.

OPEC's secretary-general said on Wednesday there was no need for the group to pump more as the price gains were due to political tensions, not a shortage of supply.

With geopolitical factors at the fore, oil traders shrugged off economic anxieties. Federal Reserve Chairman Ben Bernanke said uncertainty about the U.S. economic outlook had increased.

FRENCH STRIKE A strike by workers at the French Mediterranean oil terminal Fos-Lavera, in its third week, has begun to hit refinery output and raised concerns over Europe's ability to export fuel to the United States. Strikers were meeting port and Gaz de France officials in a fresh bid to find a way out of the 16-day strike.

Some refineries could start shutting down as soon as Friday if the dispute is not resolved, operators said. Fos Lavera is the world's third-biggest port for oil products with 64.2 million tonnes moving through it annually.

Technical analysts at Barclays Capital said oil would find it tough to break through , for the time being at least. U.S. crude hit a record .40 last July.

''All signs warn that oil will struggle to make headway above first time around and at the very least a period of consolidation is needed,'' they wrote in a report.

REUTERS PV BD1808