The United States has asked Saudi Arabia's ambassador to the U.S. to return from a trip home with information on missing writer Jamal Khashoggi.

State Department spokeswoman Heather Nauert says the ambassador is on his way back to Saudi Arabia and has been told, "When you come back we'd like to hear a report from you."

Khashoggi went missing more than a week ago after entering a Saudi Arabian consulate in Istanbul. Turkish officials allege he was killed inside the consulate.

Khashoggi's disappearance has prompted global demands for answers from Saudi Arabia, with world leaders, including U.S. President Donald Trump, registering their concern.

Nauert did not say why the Saudi ambassador, Prince Khalid bin Salman, is returning to Saudi Arabia.ry tough pill to swallow for our country."