State department warns Americans of 'potential risks' for Europe trips

The United States warned its citizens on Tuesday of the "potential risks" of European travel following a spate of terror attacks, including the latest bombings in Belgium.

"The State Department alerts US citizens to potential risks of travel to and throughout Europe following several terrorist attacks, including the 22 March attacks in Brussels claimed by ISIL," the agency said, referring to the Islamic State (IS) group. 

"Terrorist groups continue to plan near-term attacks throughout Europe, targeting sporting events, tourist sites, restaurants and transportation," it added, in a travel alert that expires 20 June.

"US citizens should exercise vigilance when in public places or using mass transportation," the State Department said.

"Be aware of immediate surroundings and avoid crowded places. Exercise particular caution during religious holidays and at large festivals or events."

It noted that European governments were also guarding against attacks and conducting raids to disrupt plots.

"We work closely with our allies and will continue to share information with our European partners that will help identify and counter terrorist threats," the State Department said.