The trial of 19 suspects believed to be involved in a spectacular $50mn diamond heist at Brussels airport in 2013, opened on Wednesday in the Belgian capital.
Spanish police on Tuesday arrested four men with alleged links to suspects held in Belgium over their involvement in the Brussels airport and metro attacks last year, officials said.
Bomb threats were reported on two aeroplanes landing at Brussels airport in Zaventem, but one plane landed safely, Belgian state broadcaster VRT reported on Wednesday evening.
The departure hall at Brussels airport, hit in March by a deadly double suicide bombing claimed by the Islamic State group, will partly reopen on Sunday, the management said.
The Belgian government appointed a new transport minister in a reshuffle sparked by allegations of lax security at Brussels airport, one of two targets hit by suicide bombers last month.
Brussels Airport cancelled half its flights on Wednesday as anger mounted over a second day of strike action by some air traffic controllers hampering a return to normality after last month's suicide bombings.
Belgian prosecutors launched a fresh appeal for help in finding a suspected third attacker in last month's bombings at Brussels airport, releasing new video footage and pictures of the so-called "man in the hat".
Brussels Airport reopened to a thin stream of passengers on Sunday, 12 days after suicide bombers destroyed its departure hall and killed 16 people.
Brussels Airport is to reopen Sunday, 12 days after its departure hall was wrecked by Islamic State suicide bombings, with chief executive Arnaud Feist announcing three flights.