Belgian police have arrested six people in Brussels as a major investigation continues into attacks that claimed 31 lives in the city on Tuesday.
The arrests were made in the Schaerbeek district. There is no word yet on the identities of the suspects or their possible connection to the attacks.
Separately, in France, a suspect who was plotting an attack has been arrested near Paris.
The Brussels bombings have been linked to last November’s Paris attacks.
So-called Islamic State (IS) has claimed the attacks in both Paris and Brussels. The arrests in Schaerbeek were made late on Thursday, and followed house-to-house searches in the area.
Residents said they heard explosions during the police raids but the cause was unclear.
Also on Thursday evening, French police launched an anti-terrorism operation in Argenteuil, north-west of Paris, following the arrest hours earlier of a man suspected of planning an attack.
Interior Minister Bernard Cazeneuve said the suspected militant, a French national, was in an “advanced stage” of a plot, adding that no connection had been made to either the Brussels or the Paris attacks.
However, French media quote police sources as saying the suspect, named as Reda K, was convicted in his absence by a Brussels court last year for recruiting IS members to go to Syria.
He was convicted along with Abdelhamid Abaaoud, considered the main organiser of the Paris attacks and killed in a police raid in Paris days later.
Last November, 130 people died after militants opened fire and detonated bombs in a number of locations in the French capital.
In a separate development, US Secretary of State John Kerry has arrived in Belgium to discuss combating terrorism. Earlier on Thursday, Belgium admitted that it had made “errors” relating to one of the Brussels attackers.
Turkey has said it arrested and deported Brahim el-Bakraoui last June, warning Belgium he was a “foreign fighter” – but the message was “ignored”. The Dutch authorities had also been alerted, Ankara said.
The Belgian interior and justice ministers said they had offered to resign over this but added that the prime minister refused to let them.
Brahim el-Bakraoui is one of three men – pictured in the middle on a CCTV image of them – who carried out the bombings at Zaventem airport that killed 11 people. Links have also emerged with Salah Abdeslam, a suspect in the Paris attacks.
Abdeslam was arrested and wounded in a police raid on a flat in the Forest area of Brussels last Friday – four days before the attacks in the Belgian capital.
Investigators say Khalid el-Bakraoui used a false name to rent the same flat.
On Thursday, Abdeslam’s lawyer said he had changed his mind and would not fight extradition from Belgium to France.
Abdeslam, a 26-year-old French national born in Belgium, did not have prior knowledge of the Brussels bombings and had stopped co-operating with police following the attacks, his lawyer Sven Mary said.
A court hearing on Thursday on the detention of Abdeslam and two other suspects has been postponed until 7 April.