ATHENS (Reuters) - Greece wants to dramatically escalate returns of migrants to Turkey in the coming weeks under a European Union deal with Ankara, the migration minister said on Friday, amid criticism it has been too slow to process them.

Migrants who will be returned to Turkey demonstrate inside the Moria registration centre on the Greek island of Lesbos, April 5, 2016. REUTERS/Giorgos Moutafis/File Photo

The deal, which has been lambasted by rights groups and aid agencies, is aimed at closing off the main route into Europe, used by around a million refugees and migrants last year. It obliges Greece to return those who either do not apply for asylum or have their claims rejected.

Officials say about 8,400 migrants are currently on Greek islands, nearly all of whom have expressed interest in applying for asylum, overwhelming the system.

Greece says that, so far, it has deported 468 people back to Turkey, none of whom had requested asylum. Just two Syrian refugees have been ordered back from Greece to Turkey and they are appealing against the decision in the Greek courts.

Migration Minister Yannis Mouzalas said Greece wanted to send thousands of migrants who arrived by crossing the Aegean Sea back to Turkey within weeks if they did not qualify for asylum in Greece.

“It would constitute failure if, within the next month-and-a-half, those who are obliged to leave the islands didn’t do so,” Mouzalas told Greek TV.

Asked how many people that amounted to, Mouzalas said “more than half” of the migrants currently there.

The minister’s comments came a day after parliament voted an amendment replacing two members of an asylum appeal board with judges.

Previously, the panel was made up of one civil servant, one member appointed by the national human rights committee, and a representative of the U.N. refugee agency UNHCR.

EU officials had called on Greece to think about whether the committee should comprise civil society members rather than judges.

Unrest in Greek island camps boiled over earlier this month as migrants stranded there since March brawled with each other and set tents on fire.

Medical aid charity Medecins Sans Frontieres said on Friday it would reject all funding from the European Union and its member states in protest at the EU-Turkey deal, which its International Secretary General said was “jeopardising the very concept of the refugee.”