The PSNI has been revealed as the second highest spending police force for informers, second only to London's Metropolitan Police.
Senior cops defended handing out brown envelopes saying they had "no doubt" it saved lives and sent criminals to jail.
A BBC investigation has found £22m was paid out to informers over the past five years across the UK.
Police Service of Northern Ireland was responsible for £1,995,392 of that figure.
While the Met paid out over £5m the third highest spender was Kent police on £1m.
The figures were obtained by a Freedom of Information request to all the UK's police forces.
There are no statistics available to show how many convictions came from information obtained.
PSNI Assistant Chief Constable Stephen Martin said: "Like any other police service in England, Scotland, Wales or the Republic of Ireland or further afield, the Police Service of Northern Ireland cannot operate effectively, nor can it fulfil its primary function to prevent and detect crime, unless it uses intelligence gathered from a range of sources.
"We have no doubt that intelligence sources under police service management have helped save lives and brought offenders to justice.
"In line with all other police services across the UK, the PSNI's policy in relation to the use of Covert Human Intelligence Sources is strictly governed by the Regulation of Investigatory Powers Act 2000 and is fully compliant with Human Rights legislation."