Known in the industry as the "mating season" and taking place alongside a conference run by industry publication Metal Bulletin, negotiations typically agree quantities and premiums paid above the London Metal Exchange benchmark aluminum price.
The aluminum market has so far been sanguine about the fallout from Rusal being placed under sanctions on expectations they would be lifted in October. The sources disagree.
"We can't agree a deal with Rusal on the basis that sanctions will be lifted by Oct. 23," a Rusal customer in Europe said. "Anyone that has a relationship with Rusal will be preparing for the sanctions to remain in place for now."
Rusal declined to comment.
Aluminum prices jumped 35 percent between April 6 and April 19 to seven-year highs of $2,718 a tonne after the sanctions were announced, while premiums for the metal on the physical market in Europe hit 3-year highs above $140 a tonne.
The metal price has since retreated to around $2,100 a tonne and the European premium to below $90 a tonne. If Rusal sells on the open market, further significant price drops are likely.
"In the current situation of complete uncertainty, Rusal cannot sign contracts for next year," a source familiar with the matter said.
The U.S. imposed sanctions on seven Russian oligarchs, including Rusal's former president Oleg Deripaska, and the 12 companies they own or control in April. Rusal last year accounted for more than 6 percent of global aluminum supplies estimated at around 63 million tonnes.
"Large scale end-customers of the company include Glencore, Toyota, SMZ JSC, Mechem SA, and Rio Tinto Inc," Rusal said in its 2017 annual report.
U.S. customers have until Oct. 23 to wind down business with Rusal, a major producer of aluminum used widely in the transport and packaging industries. European customers have to abide by the deadline if they have operations in the U.S. or if they sell to U.S. customers.
Rusal staff are expected to be in Berlin Sept. 12-14 and will meet existing and potential new customers, even though its head of sales and some marketing people left soon after the sanctions were imposed.
"Customers will be reluctant to negotiate with them this year. We can't take risks with our supply chain, we have to find alternative sources," an aluminum consumer said.
"Rusal probably won't have any contracts for next year and if the embargo is lifted they will have to sell metal on the spot market. Price volatility is going to shoot up."
U.S. premiums for aluminum in the physical market, already elevated after the announcement of import tariffs on aluminum in March, rose $70 to $490 a tonne during April and have since fallen back to around $440 a tonne.
"The market has been ignoring the Rusal conundrum since the extension of the deadline. Maybe the penny will drop in Berlin, that four million tonnes (a year) could be taken out of the market," a source at a commodity trader said.
The U.S. Treasury extended its deadline for U.S. consumers to wind down business with Rusal to Oct. 23 from June 5 and said it would consider lifting sanctions if Deripaska, ceded control of the company.
"Even if the U.S. do lift the sanctions, they won't do it until after the (U.S. midterm) elections in November," an aluminum industry source said, adding that a probe into possible collusion between President Donald Trump's election campaign and Russia would delay any action.
"The administration will not want to show any sort of leniency to the Russians before the elections, not before they know what sort of a mandate they have."
(Reporting by Pratima Desai and Polina Devitt; editing by Veronica Brown and Emelia Sithole-Matarise)
By Pratima Desai