European Commissioner for Budget and Human Resources Günther Oettinger has called on EU member states to increase their financial contributions to meet the requirements of the refugee agreement with Turkey.

"The member states will have to finance at least $2 billion," Oettinger said in an interview with Der Speigel.

Oettinger reportedly said in the interview, which will be published on Saturday, that EU member states must support the deal with funds from their national budgets.

Leading the way in humanitarian efforts for Syrian and Iraqi refugees, Turkey has spent more than $25 billion to carry out projects addressing their needs. The number of refugees now surpasses more than 3 million in Turkey.

Turkey and the EU signed a refugee deal in March 2016, to discourage irregular migration across the Aegean Sea by taking stricter measures against human traffickers and improving the conditions of the nearly 3 million refugees in Turkey. Since then, the number of refugees illegally crossing the Aegean between Turkey and Greece has dropped 85 percent, according to the Turkish Coast Guard.

The March 2016 deal employs a one-for-one formula under which failed asylum seekers in Europe are returned to Turkey while Syrian refugees are resettled in EU states in a quota system.

As another part of the deal, the EU said it would open two chapters in Ankara's EU accession negotiations, provide funding for refugees and grant visa-free travel to Turkish citizens to the Schengen zone. Ankara criticizes the EU for not holding to its promises and for not granting visa-free travel within the Schengen zone.