French police are investigating a series of abductions of cryptocurrency millionaires after storming a house near Paris and rescuing a man whose finger was severed by kidnappers demanding a ransom.

The man, who is aged about 60 and owns a cryptocurrency firm with his son, was freed by the elite GIGN police unit on Saturday night, two days after masked men snatched him from a well-to-do Paris street in broad daylight.

The scenario was almost identical to the kidnapping of the wealthy founder of a French cryptocurrency company in January, who also had a finger chopped off.

David Balland, 36, was abducted from his home by armed men. Police found him bound and gagged in the back of a van 24 hours later. His abductors had demanded a ransom of €10 million.

The kidnappers of the 60-year-old man, whose name has not been made public, demanded between €5 million and €7 million. He was described as an investor in his son’s cryptocurrency marketing firm, based in Malta.

Investigators feared he could have been harmed further had they not rescued him at 9pm on Saturday from a house in the Palaiseau area, 12 miles south of Paris. Five suspects in their twenties were arrested at the house. Two more were arrested on Sunday.

Four men wearing ski masks had grabbed the man as he walked along a street in the 14th arrondissement of Paris on Thursday morning. They bundled him into a delivery van and drove away.

David Balland, co-founder of Ledger, in an interview.

David Balland was taken at gunpoint from his home in central France

His wife said that both her husband and her son had been threatened in the past.

The kidnapping was the latest of several targeting cryptocurrency entrepreneurs in France and other European countries.

Balland, a co-founder of Ledger, a business specialising in digital wallets to store cryptocurrencies that is valued at about €1.3 billion, was abducted on January 21.

He and his partner, Amandine, were forced out of their home near Bourges, in central France, at gunpoint. They were then separated and Balland was taken to a house in the town of Châteauroux, where one of his fingers was cut off.

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Ten men and one woman, aged between 20 and 40, were arrested. Nine have been charged with abduction, including the suspected gang leader, who is 26 and has a police record for kidnapping.

In December the 56-year-old father of a French cryptocurrency influencer based in Dubai was targeted by kidnappers in eastern France. He was seized from his home and forced into a car while his wife and daughter were tied up.

His son contacted police after receiving a ransom demand, and the two women were freed within a few hours. The father was discovered alive in the boot of a car in Normandy a day later. He was bruised and had been sprinkled with petrol.

Several other abductions of cryptocurrency entrepreneurs or their partners have been reported in Spain and Belgium over the past few months.