WASHINGTON (AFP) - A prominent US lawmaker said on Wednesday (March 23) that he was convinced the deadly Brussels terror strikes could have been aimed at Americans since there were US airline counters nearby.

"From my vantage point, it does look like an attack on Americans. It looks like it was targeted towards Americans to some degree," Republican congressman Devin Nunes, the House Intelligence chair, told reporters.

Nunes noted that Tuesday's bomb attacks - which the Islamic State group has claimed responsibility for - tore through part of Brussels international airport "right by the United, American and Delta airline stands."

And the location of the Maalbeek metro station bombing was "close to the US embassy," he added.

"If you were going to pick locations where you might hit Americans, those would be the locations," Nunes argued.

Hundreds of mourners gathered in the city on Wednesday in a show of solidarity with the 31 people killed and 270 injured in the triple bomb attacks.

Earlier in the day, Belgium's King Philippe, Prime Minister Charles Michel and European Commission chief Jean-Claude Juncker led a minute's silence outside the EU headquarters in Brussels, the city that is also home to Nato.