"If America issues arrest warrants for my 13 bodyguards in a country where I went upon invitation, I'm sorry, but I will not say that country is civilised," Erdogan said at the Civilisations Forum at Ibn Haldun University in Istanbul
Turkey is hosting the summit this year in Istanbul under the theme "Expanding Opportunities through Cooperation", taking over the organisation's chairmanship from Pakistan.
After creating a stir during her election campaign with a pledge to try to get EU leaders to terminate Turkey's membership bid, German Chancellor Merkel backed down and proposed decreasing or redirecting EU funding linked to membership talks.
"What is the guarantee that 3,500 armoured vehicles and weapons that the US sent to Syria will not be used against Turkey?" President Recep Tayyip Erdogan asks during his address.
Turkey's foreign minister Mevlut Cavusoglu says the D8 countries need to cooperate more in dealing with global challenges of drought, racism, mass migration and poverty.
Meanwhile, British Prime Minister May urges EU leaders to urgently set out plans to move forward with Brexit negotiations, in particular on the rights of European nationals, as they prepared to delay key trade talks until at least December.
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