BRUSSELS (AFP) - A Frenchman who allegedly shot dead four people at a Jewish museum in Brussels was denied medical care in prison for a suspected brain tumour and is unfit for trial, his lawyers said on Thursday (Sept 21).

Mehdi Nemmouche, who allegedly carried out the May 2014 militant attack at the museum in Brussels, will refuse to appear at his trial if treatment is denied, lawyer Sebastien Courtoy told reporters.

Nemmouche, held in solitary confinement in a Belgian prison for three years, is exhibiting symptoms of "a brain tumour".

He said Nemmouche was "losing his eyesight and hearing" while suffering from "unbearable pain" in his head and cannot concentre.

"There will be no Nemmouche trial," Courtoy said. "He is physically not in a state to defend himself, nor to study the case against him."

Standing next to Henri Laquay, who is also defending Nemmouche, Courtoy blamed the Belgian prison administration, which for "unexplained reasons" has refused to allow for a brain scan recommended since April by a court-appointed doctor.

Nor was Nemmouche fit enough, they said, to be sent to France where he is due to be tried over charges he was a jailer of four French journalists held hostage in Syria.

On May 24, 2014, a gunman armed with an assault rifle opened fire in the entrance hall of the museum in the centre of the Belgian capital, killing two Israeli tourists, a French volunteer and a Belgian museum receptionist.

Six days later Nemmouche was arrested in the southern French port city of Marseille when getting off a bus from Brussels.

Nemmouche had returned from Syria where he had been fighting with Islamist extremists.

The Belgian federal prosecutor's office said Nemmouche's trial will take place next year.