Two explosions were heard as police carried out more raids in a Brussels neighbourhood today, Belgian state media reported.

One man was reported to have been detained as Belgian authorities carried out multiple operations following the terror attacks on Tuesday at Brussels airport and the Metro in which 31 people died and 270 were injured

At least one suspect in the city attacks is at large, and it is unclear whether there were other accomplices.

Six people were detained on Thursday after raids targeted central Brussels, Jette and the Schaerbeek neighbourhoods, where police earlier found a huge stash of explosives and bomb-making material in an apartment used by the attackers.

Prosecutors are expected to decide later on Friday whether to charge or release those detained

State broadcaster RTBF said several police operations were under way in Schaerbeek on Friday, and one person has been detained.

It said one explosion was heard at the start of the operation and cited witnesses describing gunfire.

A witness told RTBF they heard two blasts and shots from heavy weapons during the police raid.

A third blast was later reported from the neighbourhood.

AP reporters at the scene described hearing a new blast, though it was unclear whether it was a controlled police detonation.

About 50 officers appear to be involved in the operation.