'Minute of noise'

Belgium this week marks the first anniversary of the Brussels airport and metro bombings with ceremonies showing the heart of Europe is still beating despite the country's worst ever attacks.

Applause is set to ring out during a "minute of noise" on Wednesday as trains, trams and buses halt to remember the 32 people killed and more than 320 injured in the attacks claimed by the Islamic State (IS) group.

Belgium remains on high alert with troops patrolling the streets a year after the blasts, carried out by a network that investigators say was also behind the November 2015 Paris attacks.

"Our country is safer now," Interior Minister Jan Jambon told AFP in an interview, while warning that there was still a threat that battle-hardened jihadists fleeing the Islamic State's last stand in Syria could come home to Belgium.

The ceremonies start at Zaventem Airport where King Philippe and Queen Mathilde will lead victims, family members and rescuers in a service of remembrance for the 16 people killed there by suicide bombers Ibrahim El Bakraoui and Najim Laachraoui at 7:58 am on March 22, 2016.

The royal couple will then travel by the subway to Maalbeek metro station in the city's European quarter where Bakraoui's brother Khalid blew himself up on a crowded train at 9:11 am, killing a further 16 people.

In a break from tradition, metro staff will hold a "minute of noise", in which commuters will be invited to take part "to show that they do not forget but they will stay standing against hate and terror," Stib, the Brussels public transport company, said in a statement.

Finally the king and queen will inaugurate a new curved, steel memorial at the nearby Robert Schuman roundabout, which sits at the heart of the European Union institutions based in Brussels.