(Adds analyst comment, updates prices, changes dateline)

By Polina Devitt

LONDON, May 30 (Reuters) - Copper prices in London were

little changed on Friday, but on course for their biggest

monthly rise in eight months due to tighter nearby supply,

highlighted by the premium for nearby copper contracts against

those further out.

Benchmark three-month copper on the London Metal Exchange

(LME) was steady at $9,570 a metric ton by 1006 GMT. The

contract is up 4.8% so far in May, on track for its strongest

month since September.

The price advance is supported by declining stocks in

LME-registered warehouses , down 45% since

mid-February to 149,875 tons, the lowest in almost a year.

Copper inventories in warehouses monitored by the Shanghai

Futures Exchange rose 7.2% this week.

As Washington continues an investigation into whether to

impose new U.S. copper import tariffs, the premium of COMEX

copper against the LME benchmark remains elevated, attracting

more metal into COMEX-owned warehouses.

"The LME copper is facing a bit of a squeeze because the

COMEX stocks keep going up and the LME stocks are declining,"

said Dan Smith, managing director at Commodity Market Analytics.

The spread between the cash LME and the three-month copper

contract closed on Thursday at a premium of $51.6 a

ton, highest since November 2022, indicating worries about

nearby supply.

The premium, a market structure known as backwardation, also

reflects uncertainty about the supply from Kamoa-Kakula copper

mine in the Democratic Republic of Congo, the biggest copper

producer in Africa and one of the world's largest, Smith added.

As a group, industrial metals were under pressure as the

dollar strengthened and market optimism faded following a court

ruling that reinstated the broad tariffs imposed by U.S.

President Donald Trump.

China's futures markets have closed until June 3 for the

Dragon Boat holiday, reducing the overall trade volumes.

As to the demand side, the focus is on the official

purchasing managers' index (PMI) in top metals consumer China,

due on Saturday. China's factory activity likely contracted for

a second month in May, a Reuters poll showed.

LME aluminium fell 0.3% to $2,443.50 a ton, zinc

slipped 0.4% to $2,663.50, lead lost 0.2% to

$1,958, tin dropped 1.8% to $30,655, while nickel

rose 0.2% to $15,395.