METALS-Aluminium lurches to four-year high on renewed supply fears; copper gains

By Eric Onstad

LONDON, April 13 (Reuters) - Aluminium prices surged to a four-year high on Monday after Washington said it would impose a maritime blockade of Iran, reviving fears of supply disruptions from major Gulf producers, while copper hit its highest in a month.

Benchmark three-month aluminium CMAL3 on the London Metal Exchange rose 3.4% to $3,617 a metric ton by 1630 GMT, its highest since March 29, 2022.

The U.S. military said it will blockade all maritime traffic entering and exiting Iranian ports and coastal areas on Monday. Tehran, meanwhile, threatened to retaliate against ports of its Gulf neighbours after weekend peace talks failed.

"Aluminium begins the week at the centre of market attention after another sharp move higher... as traders absorb the implications of a full naval blockade around the Strait of Hormuz," Neil Welsh, head of metals at broker Britannia Global Markets, said in a note.

The Gulf region accounts for roughly 9% of global aluminium supply before the U.S.-Israeli attacks on Iran disrupted supplies and operations at several Middle East smelters, including Emirates Global Aluminium (EGA).

EGA said earlier this month that fully restoring production at its Al Taweelah smelter, which produced 1.6 million tons of cast metal in 2025, could take up to a year.

Supply worries were reflected in the premium of the LME cash contract over the three-month future CMAL0-3, which surged 31% to $87.25 a ton, the highest since February 2007.

LME copper CMCU3 added 1.7% to reach $13,061 a ton, its highest since March 12, while nickel CMNI3 advanced 2.9% to $17,745 after a report said that China planned to halt exports of sulphuric acid, a key input for metal refining, from May.

"This brings risks to Chile's SxEw (solvent extraction-electrowinning) copper production, and Indonesia's nickel output which was already facing disrupted Middle East sulphur supplies," Morgan Stanley analyst Amy Gower said in a note.

The red metal was also supported by firmer demand in top consumer China.

The Yangshan copper premium SMM-CUYP-CN, a gauge of China's appetite for importing the metal, jumped to $74 a ton, the highest since June 2025 and up 76% in one week.

Among other metals, LME zinc CMZN3 slipped 0.3% to $3,323.50 a ton, lead CMPB3 added 0.2% to reach $1,925 and tin CMSN3 rose 1.1% to $48,495.