The U.S. Embassy warned Friday of "a high probability" of imminent terrorist attacks in Bogota (search) and said Americans and U.S. companies may also be targeted in the coastal city of Cartagena.

The warning urged Americans to avoid major commercial, entertainment and nightlife centers for the next several days.

Bogota's two trendiest shopping and dining districts continue to be off-limits to U.S. Embassy employees, their families and embassy contractors.

Colombia's main rebel group, the Revolutionary Armed Forces of Colombia (search), known as the FARC, has carried out bomb attacks in this Andean capital in which dozens of people have been killed.

A FARC commander said on Nov. 29 that it would also attack U.S. military personnel, who have been training and advising Colombian government forces battling the 40-year-old leftist insurgency.

On Nov. 15, a rebel tossed hand grenades into two Bogota brewpubs frequented by Americans, wounding 72 people, including four Americans.

The United States has spent some $2.5 billion, most of it in military aid and training, since 2000 to help the Colombian government battle the FARC and a smaller leftist rebel group.