Turkish president Recep Tayyip Erdogan has said Donald Trump's plan to declare Jerusalem the capital of Israel is a "red line" for Muslims and could see him breaking off diplomatic relations with the country.
Mr Erdogan told parliament his country's response "could go as far as us cutting diplomatic ties with Israel."
He also said he would convene a summit meeting of countries of the Organisation for Islamic Cooperation to oppose any move recognising Jerusalem.
American officials have said Mr Trump may recognize Jerusalem as Israel's capital this week as a way to offset his likely decision to delay his campaign promise of moving the US embassy there.
His point-man on the Middle East, son-in-law Jared Kushner, later said the US President hasn't decided yet what steps to take regarding Jerusalem.