Wires

UPDATE 7-Oil falls below $64 on prospects for Saudi output restart, economic concerns

Alex Lawler

concerns@

* Saudi Arabia to restore full output by next week - source

* Business survey suggests euro zone growth has stalled

* UK believes Iran was behind Saudi oil attacks (Updates prices)

LONDON, Sept 23 (Reuters) - Oil fell below $64 a barrel on Monday, reversing an earlier gain, pressured by the prospect of a faster-than-expected full restoration of Saudi oil output and by fresh signs of European economic weakness.

A source, briefed on the latest developments in the Sept. 14 attack on Saudi oil facilities, told Reuters Saudi Arabia had restored around 75% of crude production lost.

Oil was up earlier in the session, supported by skepticism over how fast output would come back.

Global benchmark Brent crude fell 44 cents to $63.84 a barrel as of 1212 GMT, having risen as high as $65.50. U.S. West Texas Intermediate was down 38 cents at $57.71.

A survey showing euro zone business growth stalled this month, dragged down by shrinking activity in Germany where a manufacturing recession deepened unexpectedly, also weighed on oil and other markets such as equities.

"Oil prices are tracking European markets lower ... understandably knocked by the woeful manufacturing data from the bloc and the implications for global growth and demand," said Craig Erlam, analyst at OANDA.

Brent has still gained about 18% this year, helped by a supply-limiting pact led by the Organization of the Petroleum Exporting Countries, although concern about slowing economic growth has limited the advance.

Tension in the Middle East has escalated since the Saudi attack. The Pentagon has ordered additional U.S. troops to be deployed in the Gulf region to strengthen Saudi Arabia's air and missile defenses.

Britain believes Iran was responsible for the attack and will work with the United States and European allies on a joint response, Prime Minister Boris Johnson said on Monday. The United States and Saudi Arabia have also blamed Iran, which denies responsibility.

The Saudi attacks have refocused investor attention on the prospect of supply disruptions in other OPEC producers. Investors had been less concerned about supply risks due to ample supplies.

"The geopolitical risk premium has returned with a vengeance and supply-side developments have been thrust back into the spotlight," Stephen Brennock of oil broker PVM said.

"While Saudi oil facilities smolder, the potential for fresh outages in Nigeria, Libya and Venezuela continues to hang over the market." (Additional reporting by Florence Tan; Editing by Dale Hudson and Emelia Sithole-Matarise)