Palestinian President Mahmoud Abbas said on Wednesday, the Trump administration's decision to recognize Jerusalem as the capital of Israel was the "greatest crime" and a flagrant violation of international law.

"Jerusalem is and always will be the capital of Palestine," he told an emergency meeting of Muslim leaders in Turkey. He said the United States was giving away Jerusalem as if it were an American city.

"It crosses all the red lines," he said.

Abbas said it was unacceptable for the United States to have a role in the Middle East peace process because it was biased in favour of Israel.