A police officer has died and another was injured following a stabbing attack in Brussels, which a Belgian judicial official said was suspected to be terrorism-linked.

The suspected attacker was shot and “neutralised” after the stabbing and taken to hospital, Belgian police said.

“One of our patrols was attacked by a man armed with a knife,” police said.

“The two police officers then called for reinforcements. An officer from another patrol used his firearm to neutralise the attacker.”

Police added: “The two injured detectives and the assailant were taken to hospital.”

A judicial official who could not be quoted by name because the investigation is ongoing told The Associated Press there is “a suspicion of a terror attack”.

The official did not elaborate.

According to Belgian media, the attacker shouted “Allahu akbar”, the Arabic phrase for “God is great”.

Le Soir newspaper said the dead police officer was stabbed in the neck and died in hospital.

Belgian prime minister Alexander De Croo posted a message of condolence to the family and friends of the dead officer.

“Our police officers risk their lives every day to ensure the safety of our citizens,” he said.

“Today’s tragedy demonstrates this once again.”

Interior minister Annelies Verlinden said she was in contact with the Brussels mayor, police chief and security services to co-ordinate the response to the attack.

“Such violence against our people is unacceptable,” she said.

The attack took place at about 7.15pm local time.

Belgian authorities searched houses and detained eight people for questioning on suspicion of supporting Islamic State financially and through the recruitment of fighters for the Syrian civil war, federal prosecutors said on Tuesday.

The prosecutors said nine houses were searched in a district of Brussels, as well as the cities of Bruges, Antwerp and Sint-Niklaas. No weapons or explosives were found.

“Those concerned are suspected to be involved in recruiting people to leave for Syria and having financially supported IS,” prosecutors said in a statement, adding a judge would decide whether they would be detained further.

In a separate announcement on Tuesday, prosecutors said they had arrested a fourth suspect, a 43-year-old Belgian man named as Reski A., in the case of a police stabbing in August which was claimed by Islamic State.

Belgian prosecutors appealed for help in finding a man suspected of leaving a bomb at Brussels Airport on March 22, saying they were eager to find a coat he had discarded and to speak to people who saw him on his hour-long walk back into the city.

Federal prosecutors released new pictures of the suspect, dubbed the “man in the hat”, who appeared to arrive at the airport with two suicide bombers and left along with passengers after the first two bombs exploded.

In a video to accompany their appeal, investigators indicate the route the man took, out of the airport, through the nearby town of Zaventem and along a main road into the city. His last appearance on security cameras was in the district of Schaerbeek almost an hour after the bombing.

Along the way, he took off his light-coloured coat and was then seen in a light blue shirt with dark patches. He was wearing a dark hat throughout.

“It is especially the coat which interests us,” prosecutor Eric Van Der Sypt told a news conference, asking if anyone  might have seen it along the suspect’s route.

Prosecutors also want to people to come forward who might have filmed or taken a photograph of the suspect or may be able to determine where he went.

Twin bombs at Brussels Airport and another on the city’s metro killed 32 people, excluding the suspected bombers. A controlled explosion destroyed a third bomb at the airport about six hours after the initial attack.

(Reporting by Robert-Jan Bartunek; editing by Philip Blenkinsop) – for Reuters