Legislation is no guarantee that tragedies such as the eight asylum-seekers' deaths in Wexford will not happen again, the Minister for Justice, Equality and Law Reform, Mr O'Donoghue has said.
Mr O'Donoghue described the deaths as his "worst fear" but said as long as there was money to be made from trafficking, there would be criminals ready to arrange the transport and people willing to take the chance of travelling.
The Minister was speaking after visiting the scene at Wexford Business Park on Saturday after the discovery of eight bodies in a container of furniture from Italy.
He also went to Wexford General Hospital, where he spoke with the medical team caring for the five survivors.
"I am obviously shocked and deeply saddened at the terrible tragedy which has occurred. My heartfelt sympathy goes out to all the relatives of the people who died in such tragic and terrible circumstances," he said.
"I have said for a number of years that it was my very worst fear and now my fear has been realised. They met what I can only describe as a horrific death."
Mr O'Donoghue said the immigration issue was a "very sensitive one" and he defended the legislation available to the Irish authorities to deal with it.
He said the work visa programme for non-EU nationals was generous, bringing 40,000 workers into the State in the past year, but there were also strict laws to deal with those who tried to profit from bringing people into the country outside of legitimate channels.
"We introduced some very tough legislation in 1999 (the Immigration (Trafficking) Act) under which people are subject to unlimited fines, prison sentences and forfeiture of vehicles," he said, adding that new carriers' liability legislation on the way would extend the powers of the Garda.
He believed a "genuine effort" was being made by governments across Europe to tackle the problem. The night before the tragedy was discovered, he had been in Brussels at a meeting of European justice and home affairs ministers where the issue had been discussed.
He said trafficking was "big business in the organised crime world" and stressed: "We must not come away from the fact that there are people who seek to exploit human beings, who care nothing for their needs and who leave people to die in the most terrible circumstances."