METALS-Copper slips to three-week low on fund selling, worries about Middle East

(Adds analyst comment, updates prices, changes dateline)

By Eric Onstad

LONDON, June 11 (Reuters) - Copper prices drifted to their lowest in three weeks on Thursday as the U.S. and Iran exchanged more attacks, prompting funds to liquidate positions on worries about higher interest rates, weaker global economic growth and softer metals demand.

Benchmark three-month copper on the London Metal Exchange was down 0.8% at $13,407 a metric ton by 0925 GMT, having earlier touched $13,378, its weakest since May 20.

The U.S. and Iran traded air attacks for a second straight day on Thursday, undermining a shaky ceasefire.

"Copper's move lower is being driven by macro headwinds rather than fundamentals. Escalating tensions in the Middle East are fuelling inflation fears and rate hike expectations," said Ewa Manthey, commodities strategist at ING.

"Unless energy prices stabilise or rate expectations soften, copper is likely to remain under near-term pressure."

LME copper has shed about 6% since May 13, when it hit its highest in 3-1/2 months as funds piled into the market on supply issues and bullish technical signals.

Part of the recent weakness is from funds liquidating some of their long positions, traders said.

Lacklustre demand in top metals consumer China was highlighted by a 19% fall over the past 2-1/2 weeks in the Yangshan copper premium , which reflects demand for copper imported into China, to $59 a ton.

The most-traded copper contract on the Shanghai Futures Exchange lost 1.3% to 103,160 yuan ($15,223) a ton, having earlier touched its lowest since May 8.

Losses in copper were cushioned, however, by continued speculation about possible U.S. import tariffs on refined copper, which has resulted in a premium on U.S. metal and flows of material to the U.S., creating supply tightness elsewhere.

Available stocks in LME-registered warehouses have slid 37% to 226,975 tons over the past two months, according to LME data.

LME aluminium added 0.3% to $3,475 a ton on continued concern about a prolonged conflict creating shortages since the Gulf accounts for about 9% of global smelting capacity.

Among other metals, LME zinc lost 1.2% to $3,451 a ton, lead dipped 0.1% to $1,960.50, nickel shed 0.3% to $17,620 and tin edged down 0.1% to $51,885.

($1 = 6.7767 Chinese yuan) (Reporting by Eric Onstad; Editing by Jan Harvey)