Hong-Kong listed Rusal, the world's largest aluminium producer outside China, has been restoring operations after US sanctions - first imposed on Rusal and its co-owner Oleg Deripaska in April 2018 - were lifted in January this year.

Second quarter aluminium sales totalled 1.08 million tonnes, while production rose 1% to 938,000 tonnes.

The rise in sales, which outstripped production, was due in part to Rusal's sell down of aluminium accumulated while under US Office of Foreign Assets Control (OFAC) sanctions, the company said.

Sales of high value-added products rose 60% to make up 38% of total sales, compared with 29% in the previous quarter.

This "indicates a stabilisation of relations with long-term counterparties," analysts at Sberbank said.

The results are in stark contrast to the company's reported output three months ago. In April, Rusal reported a fall in total sales and a 44% year-on-year decline in value-added product sales due to the lingering effect of the sanctions, which had constrained the company's ability to sign contracts.

Analysts at VTB Capital said the second-quarter sales increase exceeded expectations, adding that implied marginal upside to their second-quarter forecasts.

They said they expected core earnings to rise more than 40% quarter-on-quarter as the business recovered from sanctions.

Rusal, however, said it expected trade tensions between China and the United States to cause uncertainty in the market and suppress economic growth.

"We are concerned that (the) overall macroeconomic situation will negatively affect aluminium demand in the second half of 2019," Rusal said.