Two men have been arrested after packages containing liquid were sent to hospitals across the UK.
Officers from the Metropolitan Police’s Counter Terrorism command seized the pair on suspicion of offences under the Malicious Communications Act.
None of the packages have so far been found to contain anything hazardous, say police.
The Met made the announcement after it was reported in the Health Service Journal that up to 25 NHS trusts had received packages from an organisation calling itself “The Cyprus Project”.
An alert was sent out by the chief medical officer warning of “a number of unsolicited packages, with accompanying literature requesting testing”.
One of the packages was received by Milton Keynes University Hospital’s research and development department on Wednesday, it is believed.
The two suspects, a 29-year-old man from the London Borough of Brent and a 37-year-old man from Harrow, were arrested in Barnet at around 6.45pm on Thursday.
They were taken into custody for questioning before being released on bail until later this month.
“Enquiries are ongoing,” said the Met in a statement.