People crowded the streets of Brussels on 22 March to pay their respects and mark the three bombings that took place in 2016. Ceremonies were held at various places across Belgium in remembrance of the victims of the suicide attacks, for which the Isis claimed responsibility.

King Philippe led a minute of silence at Zaventem Airport where two bombs were detonated and at the third blast site, Maalbeek metro station. He paid his respects to the 32 people killed and more than 320 others who were wounded.

The country also held a "minute of noise" when vehicles came to a halt and people applauded as a show of defiance.

Belgium continues to be on high alert for threats following the 2016 incident, which is regarded as the country's worst ever terror attack. "It is possible that we keep soldiers on the streets -- I am absolutely unable to tell you what situation we will be in, in one month, three months, or six months," Prime Minister Charles Michel said on RTL television.

"We will only have certainty when the situation in Syria and Iraq is resolved," one senior official told Reuters.

While 59 suspected Isis supporters have already been arrested, authorities have not been able to identify those responsible for the attack and Michel said the investigation was still open. "The attacks are inspired by IS, they are inspired by a totalitarian ideology that aims to destroy European values," the PM said. "We need to fight this ideology with full determination."

Brussels bombing anniversary
Belgium's King Philippe leaves after laying a wreath at Brussels Zaventem airport during a ceremony commemorating the first anniversary of twin attacks at Brussels airport and a metro train in Brussels, Belgium REUTERS/Yves Herman