Figures released by the PSNI following a Freedom of Information request show over £400k was paid out in the financial year 2011/12.
Intelligence gathering is an important weapon in the fight against terrorism and the figures show an increasing dependence on informants.
In 2006/7, Covert Human Intelligence Sources were paid just over £160k but by last year the figure had jumped to nearly £450k.
The fact that dissident republicans are determined to kill was demonstrated only days ago when police prevented a 60kg car bomb reaching its destination.
Police believed the target to be Lisnaskea police station, but a statement sent to UTV on Monday, which claims to be from Óglaigh na hÉireann, said the target was the Lough Erne resort, the venue for June's G8 summit.
The PSNI refused UTV's request for information on how many informants they have and whether more money was paid to loyalist or republican sources.
The use of police informers is both a controversial and sensitive issue and has divided political parties in Northern Ireland.
Arlene Foster DUP MLA said that the world of informants has always been a very dark one.
"But I think what most people will take away is the fact that the police are moving more into intelligence policing again.
"And frankly, intelligence policing brings results and we've seen that at the weekend - very personally for me in Lisnaskea my hometown.
"The fact that a bomb, was on its way there, has been stopped by intelligence policing. I very much welcome that."
Gerry Kelly MLA, Sinn Féin's policing spokesperson, said: "Any police service in the world will use informants. What is our difficulty, and we have raised this at the Policing Board, is an issue of accountability.
"Who is watching what way the public money is used?," he queried.
"And let us be very clear about this - into the very recent past we have had examples of some of these informants being completely out of control.
"Their handlers allowing them to be involved in everything right up to and including murder."