Convictions have been secured in only 24 of the 150 gangland murders committed since the Taoiseach took office in 1997, the Dail heard today.
The Labour Party called for legislation to boost measures like the witness protection programme and Garda surveillance powers.
Speaking after two more gangland killings last weekend, leader Eamon Gilmore said: "Of the 150 savage murders that have occurred in this country since you became Taoiseach, only one in six has been caught and put away out of society."
"We cannot go on having a situation where these murders are taking place week in week out. There is barely a weekend now when we don't have one of these gangland killings taking place and it cannot continue."
Bertie Ahern said the number of gangland killings in the country was completely unacceptable.
"The prosecution rate is not good," he added.
"In reality the difficulty is that these criminals, even when they are badly injured, will not co-operate with investigations or participate in the normal surveillance intelligence gathering."
"This is a big problem, when they know the gangs, they have very good intelligence on a lot of the gangs, but where there are crimes against each other, their modus operandi is not to speak."
He added: "The number of detectives who are involved in sitting in the middle, trying to stop some of these gangs engaging in criminal acts against each other, is hugely expensive. It is preventing murders. There are a number of these operations taking place in the Greater Dublin area."
Mr Gilmore claimed Mr Ahern had said at the Fianna Fail ard fheis in 1997 that he would make the fight against crime his first priority in government.
In a message to organised criminals, Mr Ahern added at the time: "Our plan is to arrest you, prosecute you and put you in jail."
PA