The U.S. Embassy in Riyadh and two other diplomatic missions in Saudi Arabia resumed consular services on Sunday after closing all of last week due to security concerns.

However, the embassy said in a statement that U.S. citizens should "continue to be aware of their surroundings and take extra precautions when travelling throughout the country." The U.S. Embassy did not immediately respond to an Associated Press request for details.

The diplomatic facilities in Riyadh, Jiddah and Dhahran closed last week after the embassy warned citizens that individuals associated with a terrorist organization could be targeting Westerners, including U.S. citizens, working for oil companies in the Eastern Province. The warning said officials received information about a threat to kidnap and attack workers.

Also on Sunday, the state-linked Saudi Okaz newspaper's website was temporarily hacked, allegedly by Islamic State group supporters. A message appeared on the paper's website encouraging Saudi citizens to revolt against their government and join the group. It also said the group was expanding.

Saudi Arabia is part of the U.S.-led coalition bombing the extremist group in Iraq and Syria. The IS group has called on its supporters to launch attacks inside Saudi Arabia.

Last year, a Saudi man stabbed a Canadian citizen while he shopped in a mall with his family in the Eastern Province. Also last year, IS group supporters shot a Danish citizen in his car in Riyadh as he left work. Both men survived the attacks.