Abdelkader Belliraj's lawyer said he had been held in solitary confinement
The trial of the alleged leader of a radical Islamist cell accused of plotting a series of killings and links to al-Qaeda has begun in Morocco.
Abdelkader Belliraj was one of more than 30 people, including six Islamist politicians, arrested in February.
Mr Belliraj is also accused of killing members of the Jewish community and an imam in Belgium in the late 1980s.
His lawyer said he would plead not guilty. He said his client was employed by the Belgian secret services.
The BBC's James Copnall reports from Rabat that the lawyer, Mohamed Ziane, made an impassioned plea for improved conditions for his client, who he said had been held in solitary confinement since his arrest in February.
Mr Belliraj and others arrested in February have been accused by the government of plotting a series of killings within Morocco.
Mr Ziane accepted that his client was found with weapons originally sent to Islamists in Algeria, and that these had later returned to Morocco.
But he also said he had been working for Belgian intelligence services.
"Belliraj says he visited the world, and terrorist organisations, in concert with the Belgian authorities, including military security," he said.
"He says this, and I will repeat it: Belliraj defended Belgium, now it's up to Belgium to defend him."
Family members and friends of the six politicians demonstrated outside the court, chanting: "We're all against political arrests."
Several of the politicians came from moderate Islamist parties.
The son of one of the politicians, Mustapha Moatassim, said his father was not guilty.
"[He] doesn't believe in violence or terrorism, and he loves his country very much," said Abdesalam Moatassim.
Some political parties and human rights groups have sprung to the defence of the politicians, our correspondent says.
There was widespread concern when two ministers appeared to suggest in February that all those arrested were guilty.
For this reason the trial is expected to be closely followed, though a verdict is unlikely before next year.