(Recasts with updated prices at 1630 GMT)

By Polina Devitt and Eric Onstad

LONDON, May 23 (Reuters) - U.S. copper prices rose to

their highest in more than three weeks on Friday, buoyed by a

weaker dollar and worries about problems at a big mine in Congo.

U.S. Comex copper futures climbed 3% to $4.82 a lb,

the strongest since April 30.

Benchmark three-month copper on the London Metal

Exchange (LME) gained 1.2% to $9,617 a metric ton by 1630 GMT,

its strongest since May 14.

Earlier base metal prices ticked lower after U.S. President

Donald Trump said he would impose 50% tariffs on goods from the

European Union, but bounced back as the dollar index fell

to its lowest in over three weeks.

A weaker U.S. currency makes dollar-priced metals more

attractive for buyers using other currencies.

Copper was also bolstered by concerns about the huge

Kamoa-Kakula copper mine in the Democratic Republic of Congo,

the biggest copper producer in Africa and one of the world's

largest.

China's Zijin Mining warned that a suspension of activity

due to seismic activity may have an "adverse impact" on

achieving planned production this year of 520,000 to 580,000

tons.

"It sounds fairly bad and obviously it's a pretty big mine,"

said Dan Smith, managing director at Commodity Market Analytics.

Co-owner Ivanhoe Mines ( IVPAF ), however, disputed Zijin's

statement, saying an investigation was still in progress.

Copper inventories in warehouses monitored by the Shanghai

Futures Exchange fell 9% to 98,671 tons this week,

while stocks in the LME-registered warehouses lost 8% to 164,725 amid continuing inflows into the COMEX-owned

warehouses . The COMEX inventories are up 3% at

174,607 this week.

In the LME system, the spread between the cash against the

three-month copper contract remained at a premium,

indicating some tightness for the nearby supply due to the

outflows from the stocks.

The premium, known as backwardation, was last at $32 per

ton.

Meanwhile, LME aluminium rose 0.4% to $2,466.50 a

ton; zinc added 0.3% to $2,705, nickel gained

0.7% to $15,605, lead climbed 1.1% to $1,991 and tin

advanced 1.6% to $32,910.