Brussels raid: One gunman shot dead as Brussels police carry out anti-terror raid

Belgian police are continuing an operation in Brussels after four officers were lightly wounded in a raid on an apartment, Belgian Prime Minister Charles Michel says.

He gave no details of the operation, which began around 2pm local time (midnight AEDT) on Tuesday.

Other ministers said two of the four injured officers had been released from hospital and stressed that the raid, linked to investigations into November's Islamist attacks on Paris, had not been expected to reveal much evidence.

The presence of French forces at the scene was a coincidence, one minister said.

A statement released by the federal prosecutor's office confirmed authorities faced one or more assailants during a major Franco-Belgian anti-terror operation on Tuesday in Brussels and killed a suspect who was armed with a Kalashnikov assault rifle.

"In this operation, one or several people opened fire on the police as they came through the door... (and) one suspect armed with a Kalashnikov type assault rifle was killed," the statement said.

The identity of this person "is being established".

After five hours of intense police activity in the area, security forces have escorted children away from nearby schools and kindergartens and begun to allow residents back to homes in the suburban neighbourhood, Reuters journalists at the scene say.

Belgium's federal prosecutor says one or more suspects barricaded themselves in an apartment after firing through a door at police who arrived to search it.

DH newspaper says one suspect was shot dead after being spotted from a police helicopter in a nearby garden.

"This operation is connected to the Paris attacks," a spokesman for the federal prosecutor said.

Gunshots were heard as police commandos crowded into the street where the raid unfolded.

Investigators believe much of the planning and preparation for the November 13 bombing and shooting rampage in Paris that killed 130 people were carried out by young French and Belgian nationals, some of whom fought in Syria for the Islamic State group.

Belgian security forces have been actively hunting suspects and associates of the militants involved in the attacks in Paris. Some of the attackers came from Brussels.

One of the prime suspects, 26-year-old Brussels-based Frenchman Salah Abdeslam, is still on the run. He left Paris shortly after his brother blew himself up in the attacks.

Belgian authorities are holding 10 people who have been arrested in the months since the attacks, mostly for helping Abdeslam.

RTBF quoted French police sources as saying Abdeslam had not been the target of Tuesday's raid.