Turkish President Recep Tayyip Erdogan has threatened to break off diplomatic ties with Israel if US President Donald Trump goes ahead with his campaign pledge to recognise Jerusalem as the capital of the Jewish state.
"Mr Trump, Jerusalem is a red line for Muslims," Erdogan said in a speech to MPs from his Justice and Development Party (AKP) in parliament in Ankara on Tuesday.
Jerusalem is claimed by both the Israelis and Palestinians as their capital. Israel considers Jerusalem to be its unified capital and in 1967 annexed the eastern half of the city, which the Palestinians say must be the capital of a future Palestinian state. The Muslim world supports the Palestinian claim and rejects Israel's annexation.
To remain neutral in the row, the international community - including the United States until now - locates its embassies in Tel Aviv.
"It could go so far that we will break off our diplomatic ties with Israel," Erdogan said on Tuesday.
He said a recognition of Jerusalem as Israel's capital would not only violate international law, it would also be "a hard blow against the conscience of humanity."
If Trump did go ahead with the move, Erdogan said he would call a summit of the Organisation of Islamic Cooperation (OIC), which Turkey currently heads, in Istanbul.
"At this summit we will mobilise the whole of the Islamic world," Erdogan said.
Trump missed a deadline on Monday to sign a waiver which would postpone moving the US embassy from Tel Aviv to Jerusalem, an election pledge he has delayed fulfilling.
If Washington recognises Jerusalem as Israel's capital, it would be the first country to do so since the foundation of the state in 1948.