Assistant Commissioner Michael O'Sullivan, who is head of the Drugs and Organised Crime Unit, also said gardaí have been investigating the Kinahan gang since 1986.

Mr O'Sullivan was speaking at a graduation ceremony at the Garda College in Templemore, where the Minister for Justice announced a large increase of the garda overtime budget for operational policing.

Frances Fitzgerald announced an extra €55m on top of the existing overtime budget of €41m.

144 new gardaí graduated from the college today, a boost to the Government's plan to bring the strength of An Garda Síochána up to 15,000.

However, 800 gardaí are due to retire this year and the Government has accepted recruitment must be increased in order to maintain the current force.

The recent O'Higgins Report on issues in the Cavan-Monaghan division strongly criticised the fact that newly-graduated gardaí were put in charge of serious criminal investigations, which led to serious flaws and failures.

An Gardaí Síochána said steps have been taken at Templemore to ensure this does not happen again.

Meanwhile, Ceejay McArdle, a three-year-old boy with Leukemia who wants to be a garda, also graduated from Templemore today.