Chelmsford Prison using dogs to improve security
Dogs will patrol the grounds of a prison as part of what officials are calling "unprecedented action".
Three German shepherds - normally used in high security prisons - are being used to improve security at HMP Chelmsford in Essex.
The Ministry of Justice (MOJ) confirmed it was committed to making the category B jail safer with the use of "patrol dogs".
Twenty eight extra prison officers will also be recruited.
HMP Chelmsford has recently come under fire for inmate drug use, increasing violence and a high suicide rate.
It was named among the 10 'most challenging' in the UK, which will together share an extra £14m of government investment.
The money will also boost prison officer numbers at the jail to 172 by the end of this year.
The prison currently holds 750 prisoners. About 60% are on remand - with the rest serving a year or less.
An MOJ spokesperson said: "We are committed to transforming prisons into places of safety and reform, and are taking unprecedented action to stop the supply and use of contraband.
"This includes a new drug testing programme, making it a criminal offence to possess psychoactive substances in prison, and setting up a specialist team of prison and police officers to tackle the threat of drones, and to bring to justice those bringing contraband in to our prisons.
"HMP Chelmsford has also had Pathfinder funds added to their existing budget, which will include spending for patrol dogs."
MOJ data shows there were 414 assaults against prison officers and inmates at Chelmsford in 2016 - compared to 131 attacks in 2013.
Dave Todd, from the Prison Officers Association, said reaction to the use of dogs among staff was "mixed".
"Unfortunately I think it's an admission that prisons are unsafe," he told BBC Essex.
"They cannot recruit enough staff and keep them in post or create meaningful regimes to allow prisoners to rehabilitate."