“It is certainly credible,” the official said on condition of anonymity. But the information was not specific about when, other than soon, where or how any attack would be carried out.

“The fact that they are trying to do something is solid,” the official told Reuters. “They want to hit targets that are important to Americans.”

The State Department on Thursday renewed a warning for US citizens to avoid travel to Saudi Arabia.

Interior Minister Prince Naif said the Kingdom did not have any information about any possible attacks.

“There is nothing that currently suggests that something like that is imminent, but given the circumstances and developments taking place (in the region) something might,” the prince said. “But we don’t have one specific piece of information to make us expect something,” he added.

Meanwhile, the search continued for a gunman who attacked George Papes, an American contractor for the Saudi Royal Naval forces in Jubail, who was injured in the attack. “He is in good condition and is expected to leave hospital soon,” a US Embassy spokeswoman said.