Palestinian president Mahmud Abbas denounced US President Donald Trump's Middle East peace efforts as the "slap of the century" on Sunday after the White House recognised Jerusalem as Israel's capital.

"We said 'no' to Trump, 'we will not accept your project'," Abbas said at the start of a key meeting of Palestinian leaders on how to face Trump's declaration.

"The deal of the century is the slap of the century and we will not accept it," he added, referring to Trump's pledge to reach the "ultimate deal" -- Israeli-Palestinian peace.