Brussels bomb suspect Najim Laachraoui is still on the run after the blasts which killed at least 34 people and left around 200 injured, including four Britons.
An arrest in connection with the terror attack has reportedly been made in the Anderlecht suburb of Brussels, but local media reports that Laachraoui had been detained were later withdrawn.
The 24-year-old, who has been linked to the atrocities in Paris five months ago, is believed to have accompanied brothers Brahim and Khalid El Bakraoui to Zaventem Airport on Tuesday, where they blew themselves up, killing 14 people.
An explosion an hour later on a train at Maelbeek Metro station killed a further 20 people and sent Brussels into lockdown.
Bomb maker Laachraoui is also suspected of having played a "decisive role" in the Paris terror attacks, French media has reported.