The 43-year-old, who was arrested in December and who has been released under investigation, is reported to have been unhappy about the NHS.

A West Mercia Police spokesperson said: ‘On 22 December a 43-year-old man was arrested in connection with a harassment offence.

‘During a section 18 search of the address officers found a 3D printer and partially complete article, which later transpired to be a non-viable plastic firearm. Both were seized by police the following day (23 December) while the man was in custody.'

The alert comes amid concerns over rising numbers of assaults on NHS staff and news of a stabbing of a nurse at The Royal Oldham Hospital in Greater Manchester on 11 January.

It is currently only an offence to own a complete 3D printed gun.

Preet Kaur Gill, Labour MP for Birmingham Edgbaston, is sponsoring a bill to make it an offence to possess any parts of a 3D printed gun.