Copper prices drifted higher on Wednesday as investors waited for details of U.S. reciprocal tariffs, but tin extended a rally to its highest in nearly three years on supply fears.

Benchmark three-month copper on the London Metal Exchange (LME) was up 0.2% at $9,711 a metric ton by 0953 GMT after slipping to its weakest in three weeks at $9,668.50.

U.S. President Donald Trump was expected to impose sweeping new reciprocal tariffs on global trading partners on Wednesday, potentially drawing retaliation from all sides. He is expected to announce the levies at 2000 GMT.

"Investors are confused, they're uncertain about the outlook. It's mostly tariff-related, although there's also global conflict, currency debasement and confusion around central bank policy," said Tom Price, head of commodities strategy at Panmure Liberum.

Trump has already imposed 25% tariffs on aluminium and steel and is expected to add duties on imports of copper.

"Aluminium gives you an insight into what copper might do. It has gone through the first phase of factoring in the cost of tariffs and now it's going into the second phase, where demand is deteriorating," Price said.

LME aluminium shed 0.1% to $2,505 a ton, having touched $2,491.50 for its weakest in nearly three months and down about 9% over the past three weeks.

LME tin gained 1.7% to $38,115 a ton after hitting $38,395 for its strongest since May 2022 on worries about supply disruptions after the earthquake in tin-rich Myanmar last Friday.

Tin on the Shanghai Futures Exchange climbed 3.9% to 297,590 yuan ($40,938.48) a ton.

Myanmar's Wa State accounts for 70% of tin production in Myanmar, the world's third-largest producer and a dominant supplier to China.

Among other metals, LME lead lost 0.6% to $1,980 a ton, zinc dropped 0.6% to $2,806 and nickel was down 0.1% at $16,090. ($1 = 7.2692 Chinese yuan renminbi)

(Reporting by Eric Onstad Additional reporting by Violet Li in Shanghai Editing by David Goodman )