Saudi Arabia on Thursday slammed US President Donald Trump's decision to recognise Jerusalem as Israel's capital, calling the move "unjustified and irresponsible".
Trump ended seven decades of US ambiguity on the status of the disputed city on Wednesday, prompting an almost universal diplomatic backlash and fears of new bloodshed in the Middle East.
He also kicked off the process of moving the US embassy from Tel Aviv to Jerusalem.
"The kingdom expresses great regret over the US president's decision to recognise Jerusalem as the capital of Israel," said a Saudi royal court statement carried by the official Saudi Press Agency.
"The kingdom has already warned of the serious consequences of such an unjustified and irresponsible move."
Saudi King Salman on Tuesday had warned Trump that moving the US embassy for Israel to Jerusalem was a "dangerous step" that could rile Muslims worldwide.
Ties between Saudi Arabia and the United States appeared to have warmed after the election of Trump, who chose the Gulf kingdom for his first overseas visit in May.
While the two countries have long been allies, Riyadh viewed Trump's predecessor Barack Obama as overly friendly with its arch-nemesis Iran.
Israel and Saudi Arabia have no official diplomatic relations.