An alert for British travellers to be vigilant was issued after Belgian soldiers shot a man suspected of being a would-be suicide bomber at Brussels Central Station.
He was shot after reportedly setting off a small explosion and no-one else is believed to have been injured.
Prosecutors in Belgium later said the man had died. They are treating the incident as a terrorist attack.
A total of 32 people were killed in attacks on Brussels airport and an underground station claimed by the Islamic State (IS) group in March last year.
The man who was shot was wearing a rucksack and a bomb belt, according to local reports. He detonated a device when he attracted the attention of soldiers in the station.
Railway sorting agent Nicolas Van Herrewegen said he had gone down to the station’s mezzanine level when he heard someone shouting.
“Then he cried ‘Allahu Akbar’ and he blew up a wheeled suitcase,” he told AFP news agency.
“I was behind a wall when it exploded. I went down and alerted my colleagues to evacuate everyone. He [the suspect] was still around but after that we didn’t see him.
“It wasn’t exactly a big explosion but the impact was pretty big,” he added. “People were running away.”
As the station and Grand Place were evacuated, businesses and restaurants were ordered to close and draw down their shutters.
Metro lines running through the station were also briefly suspended on orders of the police.
The Foreign and Commonwealth Office confirmed that there has been an incident at Brussels Central Station.
“The British Embassy is in contact with local authorities and urgently seeking further information. You should remain vigilant, avoid the immediate area and follow the advice of the local security authorities,” the FOC said last night in an updated travel advisory.