BEIJING, April 13 (Reuters) – China’s aluminium exports in March rose to their highest since June as favourable pricing led the world’s biggest producer to sell more abroad even as the nation faces scrutiny over its trade practices amid a spat with the United States. Unwrought aluminium and aluminium product exports rose 10.2 percent from a year ago to 452,000 tonnes last month, the General Administration of Customs said on Friday, the fourth-highest amount on record. Steel exports last month fell 25.3 percent from a year earlier to 5.65 million tonnes. Exports of aluminium rose just as the United States imposed a 10 percent tariff on imports of the metal on March 23 along with a 25 percent duty on steel imports. U.S. President Donald Trump called for the tariffs to protect U.S. metal makers from cheap imports. March aluminium exports were 22.2 percent higher than February’s 370,000 tonnes, customs said. Steel exports were up 16.6 percent from 4.85 million tonnes in February. Chinese aluminium shipments dipped in February but had been buoyant since November due to a favourable arbitrage to the London Metal Exchange price, encouraging producers and fabricators to seek better margins abroad. Prolonged environmental restrictions in some major Chinese steelmaking hubs have curbed steel supplies after mills were ordered to shut some production to reduce emissions. Traders and analysts expect more cities to impose restrictive environmental policies as part of Beijing’s campaign to curb air pollution, which may further rein in steel output and support domestic steel prices. “Prices for steel products in March were much higher than last year, which also dampened the incentives for exports,” said Xu Bo, an analyst at Haitong Futures. Average spot prices for rebar last month were 3,905 yuan ($620.62) a tonne, compared to 3,743 yuan a tonne in 2017, according to data from consultancy Wind. “The impact of Trump’s 25 percent tariff is limited since the policy was not fully implemented until late March,” Xu said.