Micheál Martin has accused the Government of failing to get to grips with the scale of the drugs trade.
The Fianna Fáil leader said that young people and children are being exploited and he called for an all-party approach to tackle the escalating issues.
It comes after a Europol report warned that violence and intimidation from drug gangs have had a severe impact on communities in Ireland.
Mr Martin said the report by the EU Drugs Agency and Europol was "very serious and concerning".
He said the report illustrates the degree to which violence, death, intimidation, stealing and spreading fear across every community in Ireland, is now a feature and a consequence of a rampant drug trade that is extremely valuable.
"The scale of what is revealed in the report is genuinely frightening and suggests that the state's response, and the Government's response to date, notwithstanding the good work of the gardaí, is not comprehensive enough to do what we're currently facing," he added.
"Provincial towns are now considered most attractive with direct access to local users and new customers, and with very little competition apparently for the big gangs in the provincial towns.
"Young people and children are being particularly exploited.
"I think that is something that we have to be extremely concerned about."
The report states that Irish organised crime gangs have a three-tier hierarchy structure.
Mr Martin added: "It says at the bottom tier is a large number of highly disadvantaged young people who are often addicts themselves.
"It is this tier, which carries out the bulk of the intimidation, according to your Europol, these typical activities are bullying, assaulting, stealing, vandalising and spreading fear, on behalf of the network."
He said that Ireland is now witnessing a rise in the number of children who identify themselves as gang members.
"I don't think we're getting to grips with the scale of this issue."
Mr Martin also called for Leo Varadkar to accelerate party colleague John Curran's proposed legislation which would make it a criminal offence to purchase drugs from a person under the age of 18.
Mr Varadkar said that while the Government will examine the Bill, he does have concerns that the legislation may criminalise some children in certain circumstances.
Labour leader Brendan Howlin raised the latest spate of drug-related gangland killings.
"Alongside the murders there's been a succession of attempted murders, as well as well documented evidence of intimidation, severe violence carried out by criminals involved in drug selling," Mr Howlin told the Dail.
"Seven killings in one year is the extraordinary level of violence in the north side of Dublin."
He called for a ministerial task force for Dublin's north side.
He added: "Crucially, it is essential that it looks beyond just a policing solution, but also focuses on issues of employment, educational disadvantage, and all the other factors that have in the past created fertile ground for criminals setting up networks or expanding their violent activities."
Mr Howlin also said that people want to see a visible presence of gardaí in communities.
He asked the Taoiseach why the intake to Garda College in Templemore was reduced this year from the government target of 800 to 600.
Mr Varadkar responded: "A decision has been made in consultation with the Garda Commissioner, also taking into account the recommendations of the commission of future policing, that we would recruit more civilian staff and by recruiting more civilian staff, we've been able to move about 500 gardaí, who were largely doing administration based desk jobs, into frontline policing and that's what people want."