WASHINGTON - US State Department issued a travel alert Tuesday, warning Americans about the risk of potential terrorist attacks this summer in Europe.

"We are alerting US citizens to the risk of potential terrorist attacks throughout Europe, targeting major events, tourist sites, restaurants, commercial centers and transportation," said the travel alert, which expires Aug 31, 2016.

The large number of tourists visiting Europe in the summer months will present greater targets for terrorists planning attacks in public locations, especially at large events, it added.

France will host the European Soccer Championship from June 10 to July 10. The country has extended its state of emergency through July 26 to cover the period of the soccer championship, as well as the Tour de France cycling race, which will be held from July 2 to July 24.

The alert asks Americans traveling in Europe to exercise vigilance when in public places or using mass transportation and be aware of immediate surroundings and avoid crowded places.

"I'm not aware of any specific credible terrorist threat around these events or in any particular place in Europe," State Department spokesman John Kirby said at a briefing on Tuesday.

"What we know is the continued interest by terrorist to conduct attacks against Western targets and Americans specifically in Europe," he said.