Copper prices rose on Wednesday as signs of tighter nearby supply in the London Metal Exchange system provided support, although ongoing U.S.-China trade tensions kept the growth-dependent metal in a tight range.

Benchmark three-month copper on the LME was up 0.5% at $9,639 a metric ton by 0950 GMT, after hitting a two-week high of $9,655.

Copper, used in power and construction, is up 5.7% so far this month as global trade tensions eased compared to April when U.S. President Donald Trump announced reciprocal tariffs.

Providing support to the metal are declining stocks in LME-registered warehouses , down 43% since mid-February to 154,300 tons, the lowest in almost a year.

The spread between the cash LME and the three-month copper contract was last at a premium of $40 a ton compared with $3 a week ago, indicating tighter nearby supply.

Meanwhile, Washington is continuing an investigation on whether to impose new copper import tariffs, keeping the premium of COMEX copper against the LME benchmark elevated and attracting more metal into COMEX-owned warehouses .

"If a tariff is applied, the incentive to move copper to the U.S. will cease, in our view prompting more physical flow into the LME, a price headwind," analysts at BNP Paribas said in a note.

"If there is no tariff or the potential tariff rate is far less than expected we think CME prices will collapse, with a negative knock-on impact on LME prices," it added.

BNP Paribas expects average LME copper prices at $8,610 in the third quarter before a rise to $9,180 in the fourth quarter.

From the point of view of global supply, the copper market was in a surplus of 289,000 tons in January-March compared with 268,000 tons a year earlier, according to the International Copper Study Group.

Among other LME metals, aluminium and zinc added 0.1% to $2,485.50 a ton and $2,707, respectively. Lead shed 0.3% to $1,979, tin lost 2.0% to $31,870 and nickel fell 1.7% to $15,150.

(Reporting by Polina Devitt; Editing by Jan Harvey)