The German chancellor is likely to press her Turkish counterpart on the EU migrant deal as world leaders discuss aid issues. "Doctors Without Borders" (MSF) has pulled out of the conference, saying it will be inadequate.
An idea conceived by United Nations Secretary-General Ban Ki-moon, the first World Humanitarian Summit is expected to press key donors to honor their financial commitments, particularly towards refugee aid.
While it is being held in the Turkish city of Istanbul over the next two days, representatives from more than 175 countries, UN and other aid agencies are expected to agree more efficient spending of humanitarian aid money.
As the conference got underway on Monday, German Chancellor Angela Merkel warned delegates that the current aid delivery system was not working.
"Very often, pledges are made but the money does not reach where it is most needed," she said, adding that it was vital that aid arrived quickly and efficiently in times of crisis.
The UN and their partners require nearly $20 billion (17.8 billion euros) but only a fraction has been received.
Turkish President Recep Tayyip Erdogan said currently, "the burden is shouldered only by certain countries, everyone should assume responsibility from now on," adding that Turkey had spent $3 billion (2.7 billion euros) hosting more than 2 million Syrian refugees.
Around the world, roughly 125 million people urgently need aid, including some 60 million displaced by conflict and natural disasters, according to UN figures.
Despite the summit's ambitions, aid group Doctors Without Borders (MSF) has pulled out, saying the conference would fail to address the most acute humanitarian crises. Last year, 75 hospitals managed by or supported by MSF in conflict areas were bombed.
The charity called on states to do more to end conflicts, respect international law and protect civilians from fighting.
Merkel meets Ergodan
German Chancellor Angela Merkel is one of the most high profile guests attending the summit, but several other pressing bilateral issues with host Turkey may take priority as she meets with Turkish President Recep Tayyip Erdogan later on Monday.
Merkel has been criticized as being too accommodating of Erdogan as she seeks to shore up the Ankara government's support for the EU migrant deal. In some quarters, she was also chided for siding with Erdogan after he sued a German comedian broadcaster a satirical poem.
On Sunday, German newspaper Frankurter Allgemeine Zeitung quoted Merkel as criticizing plans by the Turkish parliament to remove immunity from prosecution for around a quarter of lawmakers, which will affect mostly Kurdish MPs.
She also hit out at the stalling of a reconciliation process with Kurds, which broke down in 2015 when violence between the Kurdistan Workers' Party (PKK) and the state flared up again.
She said she planned to raise "all important issues" during her talks with Erdogan, including ongoing political tensions, the rule of law and cooperation on refugee policy.
Erdogan faces pressure
Under the EU migrant deal, Turkey has agreed to take back migrants from Greece and to prevent refugees - many from Syria and elsewhere in the Middle East - from leaving its territory.
"I am concentrating on observing exactly how Turkey handles its promises. Until now, Turkey has been implementing them reliably, and I will of course speak to the president about the state of affairs," Merkel told the paper.
Referring to EU plans to waive visas for Turks entering the EU, Merkel said the agreed conditions had to be met first: "It concerns the standards in Turkey and requires changes to be made there."
Erdogan has also refused to change the country's anti-terror laws despite pressure from the European Union.
mm/kms (AFP, dpa)