April 21 (Reuters) - Goldman Sachs on Tuesday maintained its forecast for the copper price to average $12,650 per metric ton this year and its estimate of a 490,000-ton 2026 surplus for the metal.

However, the bank flagged risks to copper supply from potential sulphuric acid shortages should disruption to shipping through the Strait of Hormuz continue.

The bank said the disruption, combined with China's decision to ban sulphuric acid exports from May 1, could tighten a market critical for copper production.

Sulphur and sulphuric acid are key inputs for solvent extraction and electrowinning, a process that accounts for 17% of global copper supply.

Goldman said the Democratic Republic of the Congo and Chile were the most exposed to disruptions in sulphur flows.

The U.S.-Israel war on Iran has hit the supply of energy goods and other materials, as Iran has effectively blocked the key Strait of Hormuz shipping artery.

President Donald Trump said on Tuesday he did not want to extend the current ceasefire and the U.S. military was raring to go if negotiations were not successful.

Companies in the DRC still hold two to three months of inventory, but if supply-chain delays extend beyond late May through June, Goldman estimates the country could curtail about 125,000 tons of production in 2026.

That curtailment would be offset by 140,000 tons of lower copper demand from weaker global growth in the bank's adverse scenario.

Separately, China's ban on sulphuric acid exports lasting through the year would put 200,000 tons of Chilean production at risk, equivalent to 1% of global supply, as the country sourced roughly a third of its acid from China in 2025, the bank added.