"Game changing" X-ray body scanners are to be installed in 16 of the most challenging prisons in England and Wales.
The instant internal images can reveal concealed weapons, mobile phones and drugs, the Ministry of Justice (MoJ) said.
Their installation at 10 other prisons in 2018 saw a drop in violence and the number of failed drug tests.
The £28m scheme is part of a £100m spend on improving prison security.
HMP Leeds governor Steve Robson said the installation of a body scanner at his jail about a year ago had been "a real game changer", as more than 300 items of contraband had since been detected.
Jails in Birmingham, Wandsworth, Liverpool, Bedford and Exeter are among the 16 prisons to get the new scanners.
Lack of scanner 'inexplicable'
The independent monitoring board at HMP Bedford said in December the prison, which has an "unacceptably high" level of violence, suffered from the lack of a body scanner.
Last June, Peter Clarke, chief inspector of prisons, said the failure of officials at troubled HMP Birmingham to secure funding for a scanner was "inexplicable".
The other prisons to benefit from the scheme are HMP Durham, Preston, Hewell, Lincoln, Norwich, Chelmsford, Winchester, Elmley, Pentonville, Bristol and Cardiff.
Inspectors at Durham Prison reported last year that almost two-thirds of inmates said it was easy to get drugs.
At HMP Pentonville, the prison's watchdog said last summer that "government neglect" had "directly contributed" to the rise in violence and drugs there.
But Prisons and Probation Minister, Lucy Frazer MP, said the project was part of an overall spend of £2.75bn "to transform our prisons".
"New technology is a vital part of our efforts to stop those determined to wreak havoc in our jails," she said.
"These scanners will help to stem the flow of contraband into jails and allow officers to focus on rehabilitation."
In 2015, the then Justice Secretary Chris Grayling said a new generation of scanners were to to be purchased because of the continuing problem with drugs being smuggled into jails.
The predicted cost of installing them in every prison in England and Wales was estimated at £15m.
The installation at the 16 prisons will begin in the spring with all scanners expected to be in place by the summer, the MoJ said.
Frances Crook, chief executive of the Howard League for Penal Reform, questioned the cost of the scanners to solve the problem of the "scourge" of drugs in jail.
"It requires a lot of staff time to monitor scanners, and that is staff time that would be better deployed in building relationships and working with prisoners to keep them busy, occupied and out of trouble, she said.
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