German Foreign Minister Heiko Maas called on the European Union to update its migrant deal with Turkey, as he highlighted the importance of further funding.

"We need an update to our migration cooperation with Turkey," Maas told Die Welt newspaper in comments published Monday.

The EU is very interested in the migration deal with Ankara being further developed and updated, he said.

"In all the difficulties we have with the Turkish government, we must acknowledge that the country has taken on a not inconsiderable migration burden for us," Maas said.

A new agreement would require the EU to provide further funding for Turkey.

"I don’t want to put any numbers out into the world, but it is completely clear that it won’t work without money," Maas said.

Among other things, the refugee deal between the EU and Turkey helps Ankara crack down on unauthorized migration to the EU and for Greece to send migrants who have reached the Aegean islands illegally back to Turkey.

In March 2016, the EU and Turkey reached an agreement to stop irregular migration through the Aegean Sea and improve the conditions of more than 3 million Syrian refugees in Turkey.

The deal has been successful in stemming the flow of migrants and refugees, but the EU’s reluctance to take in refugees from Turkey, and bureaucratic hurdles in transferring promised funds for refugees, have led to sharp criticism from Turkish politicians.

President Recep Tayyip Erdoğan criticized the EU for failing to fulfill its pledge to provide funding for migrants and refugees in Turkey as part of the pact while allocating billions of euros to Greece.

Essentially swapping migrants, the EU also promised to accept one Syrian eligible for asylum for every Syrian who was returned to Turkey from the Greek islands without having received asylum. As a result of this, thousands of Syrians have been resettled in the EU, though this pales in comparison to the millions of Syrians Turkey is estimated to be hosting.

By March 2021, only 2,140 migrants have been sent back to Turkey under the pact, which is also due to the overwhelmed asylum system in Greece that drags procedures on for years.

The deal reduced the number of migrants reaching Europe, while Turkey received most of the 6 billion euros ($7.15 billion) in EU support.

Five years on, the pact is failing as Turkey struggles with the increased number of migrants, while the EU is more divided than ever over its asylum policy.

Turkey is hosting 6 million migrants, with nearly 4 million from Syria, its migration authority says. That's 2 million more than in 2016, a heavy burden on a country that only had 60,000 asylum-seekers in 2011 before Syria's civil war broke out.

The pact nearly collapsed last year when thousands of migrants, mostly Afghans, Pakistanis and Iraqis, amassed at the Turkish border with Greece after Ankara opened its borders for those heading to Europe, fearing more refugees from Syria's Idlib.

The border crisis was interrupted by the outbreak of the pandemic.

Since the accord, the number of migrants and refugees arriving in Greece has fallen sharply.

In 2015, at the height of the crisis, 856,000 crossed the Aegean Sea. This figure dropped to 173,000 the next year and to only 30,000 in 2017.

In 2020, likely because of the coronavirus pandemic, just 10,000 crossed.