ABU DHABI, 9th March, 2016 (WAM) — The United Nations’ refugee agency said proposals to send back refugees en masse from the European Union to Turkey would contravene their right to protection under European and international law.

“The collective expulsion of foreigners is prohibited under the European Convention of Human Rights,” Vincent Cochetel, Europe regional director of the U.N. High Commissioner for Refugees (UNHCR) told a news briefing in Geneva.

Turkey offered on Monday to take back all migrants who cross into Europe from its soil in return for more money, faster EU membership talks and quicker visa-free travel for Turks. EU leaders accepted the offer in principle.

“As a first reaction, I am deeply concerned about any arrangement that would involve the blanket return of anyone from one country to another without spelling out the refugee protection safeguards under international law,” Filippo Grandi, the United Nations High Commissioner for Refugees, was quoted by the agency’s website as saying.

Grandi, who was speaking to the European Parliament in Strasbourg on the occasion of International Women’s Day, stressed that legal safeguards would need to govern any mechanism under which responsibility would be transferred for assessing an asylum claim.

“An asylum-seeker should only be returned to a third state, if the responsibility for assessing the particular asylum application in substance is assumed by the third country; the asylum-seeker will be protected from refoulement; and if the individual will be able to seek and, if recognised, enjoy asylum in accordance with accepted international standards, and have full and effective access to education, work, health care and, as necessary, social assistance,” he detailed.

The U.N. Children’s Fund also voiced deep concerns about the migrant plan, noting that 40 percent of refugees were under 18.

“First and foremost children’s rights to claim international protection should be guaranteed. Children should not to be returned if they face risks including detention, forced recruitment, trafficking or exploitation,” UNICEF spokeswoman Sarah Crowe said.

UNICEF said in the immediate term, the current dire situation unfolding on the borders of Greece and the Former Yugoslav Republic of Macedonia, remains unacceptable for children who are now in the majority of those on the Idomeni border in northern Greece.