BEIJING: China's July aluminium imports leapt nearly sevenfold year-on-year to their second-highest level on record, customs data showed, as a rare price phenomenon saw the world's top exporter of the metal turn net importer for the first time since 2009.

Arrivals of unwrought aluminium and aluminium products into China came to 391,297 tonnes last month, the General Administration of Customs said on Sunday.

That is the highest monthly total since April 2009, when China imported almost 440,000 tonnes. It was up 570% from July 2019 and up 35.5% from 288,783 tonnes in June this year.

The import volume beat China's July export total of 373,402.3 tonnes reported by customs earlier this month.

That means China, by far the world's biggest producer of aluminium, was a net importer of unwrought aluminium and aluminium products last month for the first time since September 2009, according to Refinitiv Eikon data.

The bumper imports came amid a wide disparity between aluminium prices in China, where demand has rapidly recovered since the coronavirus outbreak earlier this year, and lower international prices on the London Metal Exchange.

The spread between the two prices, known as an arbitrage, meant Chinese consumers - who usually have little need for foreign aluminium - were able to source metal more cheaply from overseas.

With London aluminium prices rising by 5.8% in July, this arbitrage window has now shut, but large volumes were still coming into China because contracts to ship the metal were signed earlier when the arb window was open, said CRU analyst Wan Ling.

Customs is due to release a breakdown of imports by origin and type of aluminium and other commodities on Tuesday.