Police in Spain say they have smashed a massive international money-laundering ring centred on the southern coastal resort of Marbella.
It was Spain's biggest investigation
Forty-one people of at least five nationalities were arrested.
The group is suspected of laundering more than $300m (£155m) for gangs involved in murder, drug trafficking, arms dealing and prostitution.
Spanish authorities said they suspected some of the cash was illegally siphoned from Russian oil company Yukos.
A spokesman for Yukos has denied any involvement in money-laundering.
A boat, two planes and more than 40 luxury cars were also seized in the raid which went ahead after 10 months of investigation, officials said.
Spanish, French, Finnish, Russian and Ukrainian nationals were among those arrested.
Interpol and Europol were both involved in the joint Spanish-Russian operation, nicknamed White Whale.
The Spanish interior ministry described it as its biggest investigation.
Large sums are thought to have been diverted from Yukos to a Dutch company and then to one of its Spanish branches, the ministry said.
The Russian oil giant has been under investigation by Russian authorities seeking the repayment of $28bn (£15bn) in alleged unpaid taxes.
The company's founder, Mikhail Khordokovsky, has been in jail since October 2003 and faces separate fraud and tax evasion charges.
Company spokesman Alexander Shadrin denied all wrongdoing in an interview with Moscow Radio, Russia's Interfax news agency reported.
"The only place left to look is on Mars - did we launder something there?" he said.
Spain's Costa del Sol, a coastal strip including Marbella and the city of Malaga, has long played host to a number of international criminal gangs, earning the nickname "Costa del Crime".