Two men have been arrested after a number of packages containing liquid were sent to hospitals across the UK, police said.
The men, aged 29 and 37 and from north London, were both arrested on suspicion of Malicious Communications Act offences on Thursday evening, the Metropolitan Police said.
They were detained in Barnet and taken into custody at a north London police station. Both have since been bailed until late August.
Chief Medical Officer Prof Dame Sally Davies said in an official warning sent to health service chiefs on Thursday that multiple parcels had been received.
“An organisation identifying itself as ‘The Cyrus Project’ has sent unsolicited packages, with accompanying literature requesting testing on the enclosed sample, to a number of health related organisations over the last 24 hours,” Davies wrote.
Tests found the packages and their contents to be non-hazardous, but Davies advised any NHS staff who come into contact with a parcel to wear synthetic rubber gloves and quarantine it in a “secure leak-proof container”.