It comes after a catalogue of serious incidents at the hospital which included the death of a patient killed in a road accident after he absconded from A&E.

From Monday, guards will be keeping watch around the clock over wards, corridors and public areas of the hospital, as well as offices and staff accommodation.

The team from Securitas underwent staff induction yesterday at the QEH, and familiarised themselves with the layout of the hospital prior to taking up official duties next week.

They will be based near the main entrance to the hospital, in the A&E department.

Until now security issues at the hospital have been supervised by a full-time security management specialist.

Hospital porters have been doubling-up as security back-up whenever they were needed to help deal with an incident or security problem.

A hospital spokesman said: 'In general terms security has never been as much of an issue here as, for example, inner city hospitals.

'Even so, we have a duty of care to our patients and staff and we have to ensure that an adequate level of protection is in place for the occasions when there are problems.

'The team from Securitas is being regarded very much as part of the wider hospital team and will be providing a polite but reassuring presence.'

Incidents highlighted in a report last summer also included a patient trying to hang themselves in A&E and the theft of laptops and dictaphones.

A report to the board of NHS Norfolk said there was an increase in what the health service describes as 'serious incidents' at the QEH from 10 in 2009/10 to 15 in 2010/11.

The hospital also tightened security regarding foreign patients last summer, after it emerged the NHS had written off millions owed by foreign nationals, who came to Britain for free treatment they were not entitled to.