Medical aid charity Médecins Sans Frontiéres said it will reject all funding from the European Union and EU member states in protest at a deal by the bloc to stem the flow of migrants and refugees via Turkey.
"What the EU-Turkey deal is today is the latest in a long line of policies that really go against the fundamental principles that enable assistance to be provided to people in acute need," Jerome Oberreit, MSF's International Secretary General, said.
"This is jeopardising the very concept of the refugee."
The group singled out the EU's deal with Turkey in March to stem the biggest flow of migrants into the continent since World War II.
Under the deal, Turkey agreed to take back all migrants and refugees landing in the Greek islands, and to crack down on people smuggling over the Aegean Sea.
In exchange, the EU said it would resettle one Syrian refugee from camps in Turkey for every Syrian that Ankara takes back from Greece.
Turkey was also offered visa-free access, increased aid and an acceleration in EU accession talks if it met certain conditions including changes to Ankara's anti-terrorism laws.
MSF Ireland issued a statement saying it "has been treating the medical consequences and witnessing the inhumanity of European deterrence policies first hand".
"Policies which have fuelled the humanitarian crisis that our teams are responding to today in Europe and beyond.
"The enforcement of migration cooperation deals between the EU and its member states with third countries is resulting in unacceptable humanitarian consequences," said Jane-Ann McKenna, Director of Médecins Sans Frontières in Ireland.
A spokesperson for MSF Ireland added that the charity will continue its humanitarian operations "full throttle", but without Irish, EU member states and European institutional funding.
The charity said "this principled decision" to not take the funding will not affect its ability to treat its patients.