The Foreign Office gave no details about its information, but said its warning against all but essential travel in Saudi Arabia remained in place.
The Foreign Office said it had updated its travel advice, saying, "We advise British nationals against all but essential travel to Saudi Arabia. We believe that terrorists may be in the final phases of planning attacks."
A statement posted on the department's Web site advised travelers to make sure they had confidence in their security arrangements and that visitors to military buildings should take special care.
On Thursday, Australia warned that another terrorist attack was expected in Saudi Arabia and urged its citizens to avoid going there. It also authorized families of Australian Embassy staff to leave Riyadh, the Saudi capital.
On May 12, car bomb attacks on three Western housing compounds in Riyadh killed 26 people and the nine assailants. Saudi Arabia cracked down on Islamic militants in highly publicized raids after the suicide attacks.