A man wearing a fake explosive belt sparked a major security alert in Brussels by claiming he would be blown up outside a shopping centre.

Police said the man claimed to have been abducted and dropped off at the City 2 complex. He said that the "suicide belt" would be detonated remotely. The suspect later admitted that he had made the whole story up.

Belgium has been on at least its second-highest security alert level for about eight months since the November 13 massacres in Paris that killed 130 people.

On March 22, suicide attacks on the Brussels underground and airport killed 32 people and injured hundreds. Extra police and military have been mobilised, guarding major buildings, nuclear plants and parts of the transport network.

Police searched the home of the mother of the suspect, a man in his 20s identified in official documents only as JB, finding materials that had apparently been used to make the fake belt, Brussels prosecutor Rym Kechiche said.

Confronted with this information, JB admitted falsifying his story. He said he had given police the licence plate number of a car he spotted in a street. The driver of the vehicle was questioned and then released.

Prosecutors said JB, who had recently informed police that he had been enlisted to join the Islamic State extremist group in Syria, was known to police and is thought to have had psychiatric problems. He has been remanded in custody over the hoax and a psychological assessment has been ordered.

Straight after the pre-dawn alert, Prime Minister Charles Michel changed his morning programme and a meeting of the Belgian crisis centre was called.

"The situation is now under control. The security services remain extremely vigilant," Mr Michel said.

Crisis centre spokesman Peter Mertens said the nation's security alert had not changed.

Mr Mertens said: "That level, and the measures accompanying it, is already high. The situation of this morning has no impact on the existing measures."

At the scene, police in hoods and military wearing helmets were seen patrolling around at least one major entry to the City 2 shopping centre, and the demining squad was also called in. Some entries to the subway station were blocked, and underground traffic disrupted.

The alert was similar to an incident in Paris in January, when police shot to death a man wearing a fake explosives vest and carrying a butcher knife as he threatened officers. The man carried a document with an emblem of the Islamic State group, but his family in Tunisia insisted he was not an extremist.

Belgium has been on high alert over the last week following a series of arrests and police raids linked to suspected terror attacks.

Over the weekend, authorities charged three men with terror-related crimes after two days of raids and the detention of 40 people in a major investigation which they said required "immediate intervention".

Unconfirmed media reports suggested that a shopping complex, an American fast food chain and police were among the possible targets. Security was visibly higher immediately after the reports surfaced, although police denied that it was boosted in response to the news.