US authorities got a tip-off from a ship design company before seizing a Russian oligarch's $90 million superyacht

• A manager at a ship-design firm told US officials that the yacht belonged to Russian oligarch Viktor Vekselberg.
• The $90 million superyacht, Tango, was then seized in Spain on Monday.

A $90 million superyacht belonging to a Russian oligarch was seized after US authorities received a tip-off from the company that helped design the vessel, court filings show.

The 255-ft Tango was seized on the Spanish island of Mallorca on Monday at the request of the US Justice Department. According to a seizure warrant, the owner is Viktor Vekselberg, the founder of Russian conglomerate Renova Group, who was sanctioned by the US last month.

According to the legal filings setting out proof of ownership of the superyacht, a manager at a company which provided services to Tango whilst it was being designed told US authorities that the vessel was built for Vekselberg and that he was the owner.

The filings didn't disclose the names of the company or employees who spoke to US officials. Instead, it referred to the manager as "W-1" and the company as "Company A."

The manager at Company A said that "Vekselberg and his home office were involved in certain details of the TANGO's design," according to the filings, and added that "employees met with Vekselberg and his staff at various points in the yacht design/build/delivery process."

The manager said that the yacht was held in the name of a shell corporation called "Arinter," but said that they knew that Vekselberg was the "true owner and user" of the vessel, according to the filing.

The DOJ said in a press release about the seizure that Vekselberg used shell companies to hide his ownership and "avoid bank oversight into U.S. dollar transactions related thereto."

Before Vekselberg was sanctioned, he sent payments from his account to Arinter and its managers, the filings said, adding that "these payments are consistent with Vekselberg being the true owner and user of the TANGO."

Another Company A employee, referred to as "W-2," "worked with Vekselberg and his wife to arrange details related to the construction of the TANGO," the filing said.

"W-2 personally met with Vekselberg and confirmed that Vekselberg was the beneficial owner of the TANGO," according to the filing.

According to the filing, Company A, W-1 and W-2 were told that the statements they made to the government would not be used against them in criminal prosecution and they were "not targets of the government's investigation."

The superyacht, which was built in 2011, can accommodate a total of 36 guests and crew, according to Super Yacht Fan. It is the first yacht to be seized by the US under sanctions levied against Russia following Moscow's decision to invade Ukraine.