BRUSSELS (Reuters) - A Frenchman accused of killing four people at a Jewish museum in Brussels refused to answer questions in court on Tuesday, his lawyer said, at a trial regarded by prosecutors as the first over an attack by a European former fighter in Syria.

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Highlighting the threat posed by returning Islamist fighters, Mehdi Nemmouche, 33, faces life in prison over the shooting in May 2014 after returning from the war in Syria.

Nemmouche has admitted to carrying a Kalashnikov, a revolver and ammunition similar to that used in the shooting, weaponry that was displayed in the court room on Tuesday.

His lawyer, however, told the jury that he did not pull the trigger in the attack that killed an Israeli couple and two museum staff, Belgian public broadcaster RTBF said.

His defense lawyer alleged the camera footage of the shooting used by prosecutors was faked and blamed the shooting on Israel’s Mossad spy agency.

Nemmouche, who appeared alongside his alleged accomplice in court, said he would not take the stand because witnesses who could have spoken in his favor were not allowed to appear.

Investigators say it is the first trial over an attack staged by a Western European returned from fighting in Syria.

A group of French journalists kidnapped and held hostage by the Islamic State have identified Nemmouche as one of their jailers and accused him of torture.

They also named as one of their guards Belgian Najim Laachraoui, who investigators say built the suicide vests used in the 2015 Paris attack and was one of two suicide bombers who attacked Brussels airport four months later.

Tracking such battle-hardened fighters is of paramount concern to Western counter-terrorism officials. Of more than 5,000 Europeans - most from Britain, France, Germany and Belgium - who joined the ranks of fighters in Syria and Iraq, some 1,500 have returned and 1,000 were killed, according to Europol.