The Immigrant Council says there is an "urgent need for Ireland to speak up"
More than 500 people have died attempting to cross the Mediterranean so far this year.
The Immigrant Council of Ireland say this underlines "the urgent need for Ireland to speak up and demand an effective European response to a humanitarian crisis".
The International Organisation for Migration (IOM) confirmed that 531 people are lost or missing, with 43 lives lost in the past week.
The Immigrant Council says the death toll - as well as an 800% increase in the numbers of people making the longer and more dangerous crossing from Libya to Europe - show that policies to date "have failed those fleeing war and terror".
It is calling on the acting Taoiseach Enda Kenny, and his acting ministers, to immediately demand the EU put in place genuine safe alternatives for people to reach Europe.
Brian Killoran, chief executive of the Immigrant Council of Ireland, said: "The deaths of 500 men, women and children since the start of the year is a damning indictment of the failed policies, broken commitments and indifference of Europe’s leaders to a crisis which has unfolded before our eyes".
The Immigrant Council adds that the death toll is on a par with that of the first three months of 2015.