A man counts Saudi riyal banknotes at his jewelry shop in Tiba market in the capital Riyadh on October 3, 2016.

Saudi Arabia's riyal was quoted at 3.7514 to the U.S. dollar in the spot market early on Monday, its weakest rate since June 2017, Refinitiv data showed.

The central bank maintains a peg of 3.75 riyals to the dollar, and usually, the currency fluctuates in a range of about 3.7498-3.7503.

Saudi financial markets have come under pressure in the last few days as U.S. President Donald Trump has threatened to punish Riyadh if it turns out that Saudi journalist Jamal Khashoggi, who has disappeared, was killed in the Saudi consulate in Istanbul.