Four people have been detained in a series of raids in Brussels linked to the failed bombing at a railway station this week by a man shouting "Allahu akbar", Belgian authorities said.
The four were picked up during searches in the Molenbeek neighbourhood, as well as in Anderlecht and Koekelberg, the federal prosecutor's office said.
The attacker in Tuesday's violence at Brussels Central Station was a 36-year-old Moroccan national also living in Molenbeek, but he was not known to authorities for being involved in extremist activities.
Many of the suspects linked to attacks in Brussels and in Paris in November 2015 lived in or passed through the Molenbeek neighbourhood.
Prosecutors said in a statement that the four suspects allegedly linked to the latest incident in Brussels were "taken in for thorough questioning" and that an investigating judge would decide whether to keep them in custody.
Authorities did not say whether anything had been seized in the raids, and declined to provide further details.
The raids are among several launched since Tuesday's attempted attack at Brussels Central Station in which the man blew up a device that did not fully detonate.
He was then fatally shot by soldiers after charging at them while shouting "Allahu akbar", the Arabic phrase for "God is great". No-one else was hurt.
Belgium has been on high alert since suicide bombers killed 32 people at the Brussels airport and a subway station last year.
Authorities said the quick shooting of the attacker averted fatalities.
He had been trying to detonate a larger nail bomb.
"It was clear he wanted to cause much more damage than what happened," federal prosecutor Eric Van der Sypt said.
"The bag exploded twice, but it could have been a lot worse."