British police said on Tuesday they had arrested eight people as part of an investigation into the SIM-swapping hijacking of U.S. celebrities' phones.

Britain's National Crime Agency (NCA) said sports stars, musicians and their families had been targeted by the scam in which criminals gain access to their victim's phones or accounts.

This allowed them to steal money, bitcoin and personal information, as well as hack their victims' social media accounts to post content and messages, the NCA said.

The investigation, which involved the U.S. Secret Service and the Federal Bureau of Investigation (FBI), discovered a network operating in Britain. The British police said eight suspects, aged between 18 and 26, had been arrested in England and Scotland.

"This network targeted a large number of victims in the U.S. and regularly attacked those they believed would be lucrative targets, such as famous sports stars and musicians," said Paul Creffield, head of operations in the NCA's National Cyber Crime Unit.

"As well as causing a lot of distress and disruption, we know they stole large sums from their victims, from either their bank accounts or bitcoin wallets."

SIM-swapping involves cyber crooks taking control of a victim's phone number by essentially deactivating their SIM and switching the allocated number to a SIM belonging to one of the criminal gang.

The criminals then reset passwords on apps, giving them access to their victims contacts, banking details, emails and social media accounts.