The Irish Prison Service says up to 14 major gangs are operating in the country's jails.
It also says the number of protection orders has increased due to the problem of drugs and drug debts of offenders.
A new joint initiative by the Prison and Probation Services is aiming to reduce reoffending and improve prisoner outcomes.
Michael Donnellan from the IPS says the level of criminality on the streets in reflected in prison.
"So we have calculated that there is 12-14 major groupings within the prison service that we are managing on a daily basis,"
"There is no doubt that's linked to drugs, it's linked to debts of money that people are owed.
"But we are doing everything that we can to try and give people in prison a proper regime."