The former president Mrs Mary Robinson has attacked Ireland's temporary work visa system, claiming it creates a situation which "frighteningly resembles bonded servitude".
She said the current system - which ties the worker to a specific employer - must be ended, as it left workers vulnerable to abuse.
"Immigrants cannot afford to lose their job as their residency in the State is tied to that specific employer. Workers may be paid below the minimum wage, subjected to abuse - including sexual abuse and harassment - and required to work illegally long hours in unsafe conditions."
The temporary work visa system was also criticised as being "a terrible mistake", by former US Congressman, Mr Bruce Morrison, who was responsible for the 50,000 "Morrison" visas given to Irish nationals in the late 1980s.
"It's taking people temporarily for permanent jobs," he warned. "That's an abusive way to think about immigrants. That is not the way to treat people. That is no way to build strength in the economy."
Both were speaking at a conference in Dublin yesterday, organised by the Immigrant Council of Ireland.
Mr Morrison also said that Ireland was not addressing the immigration issue properly, and that the Government would have to develop comprehensive and thoughtful policies.
"Ireland has to face up to its role as a destination country ... If it fails to do so, it will pay the price in the decades and centuries to come."
He said that the scale of this problem was not appreciated yet in Ireland.
"Ireland's current rate of immigration per capita is double that of the US. What we're dealing with here is big numbers."
Calling for a rights-based approach to immigration, he said that it should be seen as being of great benefit to an economy and society, rather than a burden.
Immigration is good for the economy, he said, calling immigrants the "self-selected thrivers of this world".
He warned against Irish people looking on it as a charity situation.
"I think it's a very dangerous way to think about it ... When you give charity, you create victims."
Mrs Robinson, the former UN High Commissioner for Human Rights, also urged the Government to sign and ratify the UN Convention on the Protection of Rights of All Migrant Workers and Their Families, which no developed nation has ratified.
Mrs Robinson noted the high numbers of asylum applications in Ireland and the fact that 90 per cent are refused as indicative of failings in the immigration system as a whole. This indicated that adequate routes for entering and working legally in Ireland do not exist, she said.
"We must urgently implement a rights-based, humane, coherent and transparent immigration policy that rectifies these problems."