The U.S. State Department on Wednesday issued an alert to American citizens and U.S. interests worldwide on "terrorist actions and violence" by Al Qaeda and other militant groups.

The broad warning recommends that all U.S. nationals "maintain a high level of vigilance" and take appropriate measures to guard and increase their security.

The alert comes days after the attack by Somali-based Islamist militant group Al Shabab, which is linked to Al Qaeda, on a shopping mall in Nairobi, Kenya, in which at least 72 people died.

The State Department warned that militants could strike at sporting events, offices, hotels, and many other places, and the attacks could be in the form of suicide operations, assassinations, kidnappings, hijackings and bombings.

The alert said that Al-Qaeda, its affiliated organizations and other terrorist groups continue planning terrorist attacks against U.S. interests in multiple regions, including Europe, Asia, Africa and the Middle East.

It also said that other targets might include "residential areas, business offices, hotels, clubs, restaurants, places of worship, schools, public areas, shopping malls, and other tourist destinations both in the United States and abroad where U.S. citizens gather in large numbers."

The department also reminded U.S. citizens of past attempted terrorist strikes on tourism infrastructure and public transportation networks in New York, London and Moscow. EFE