The government has revised and updated a warning to Americans about terror in the Philippines (search), urging U.S. travelers to "exercise great caution" there.

The State Department announcement renewed an announcement issued in July. The agency said terrorist activity in the Philippines remains high, including several bombings in Mindanao (search), the largest island in the southern Philippines. The department singled out two terror groups, the communist New People's Army, which operates throughout the country, and the southern Abu Sayyaf (search) Muslim extremist group, which the Philippine government says is loosely aligned with the al-Qaida network.

Both groups, the State Department said, are responsible for killings and hostage takings.

"In view of a number of security-related incidents and the possibility of future terrorism and other violence or criminal activity, Americans traveling to or residing in the Philippines are urged to exercise great caution and maintain heightened security awareness," the department said.

The State Department also issued a new warning urging U.S. citizens to re-evaluate plans to travel to Djibouti in the Horn of Africa, where U.S. troops are based in connection with the fight against terror. Terrorist threats have been made against American and other Western interests in Djibouti, said the announcement, an update of an Oct. 14 warning.

The department said Americans should remain vigilant, especially in restaurants, hotels and other public places, and should avoid large crowds.