French Interior Minister Manuel Valls on Tuesday ordered to strengthen security measures and urged high vigilance to secure French interests and citizens from potential terrorists' threats after Boston explosions.

Interviewed Tuesday morning on French radio RTL, Valls confirmed to keep the "Vigipirate" alert at "reinforced red," a relatively high security alert.

"Every time there is an event like this with worldwide impact, it's necessary to remind people we're mobilized and vigilant," said Valls.

Two bombs exploded on Monday in the crowded streets near the finish line of the Boston Marathon in the United States, killing at least three people and injuring more than 140 in a bloody scene of shattered glass and severed limbs.

On Monday midnight, the French interior ministry acted quickly by issuing a statement on strengthening nationwide security control.

In the statement, the minister called on "the internal security forces to immediately strengthen patrols' presence in line with the Vigipirate Plan" mainly in public places.

Valls also asked French citizens to be vigilant and stressed the necessity to "strictly respect the instructions issued by the security services," and to report any suspicious packages.

France has been the target of terrorist groups' attack following its military commitment mainly in Afghanistan and in Mali.

The calm in Paris was broken in 1995 with a major bomb in the capital subway that killed eight people and injured 200.