Tens of thousands of Yemenis took to the streets after Friday prayers in the capital Sanaa demanding the prosecution of Ali Abdullah Saleh, the longtime autocratic leader who stepped down in February after a year-long uprising.

Protesters raised banners reading, “The trial is coming.” Witnesses say demonstrators marched in other Yemeni cities as well.

Saleh signed a power transfer deal that gave him immunity from prosecution in return for leaving office.

However, his public appearance earlier this week in a celebration at the headquarters of his ruling party, which he still heads, sparked public anger and renewed calls for his prosecution over the deaths of protesters and over corruption.

Saleh continues to exert considerable influence through family members in key positions in the security forces. Yemen’s new President Abed Rabbo Mansour Hadi has tried since assuming office to purge Saleh associates from key positions, but critics of the ousted president say he is still using his allies to stir unrest.

“The revolutionary (crowds in the) squares will not permit a continued political role of the ousted president or a return of the old regime,” said Abdel-Hadi Al-Azazi, a leading youth activist.

Meanwhile, the military is engaged in a broad offensive against Al-Qaeda in the south of the country, retaking in the summer several towns that had been captured by the militant movement during last year’s unrest.

The Defense Ministry said in a statement that security forces arrested on Friday four Al-Qaeda militants in the capital in connection to assassination of a Yemeni intelligence general last week.

A security official said that anti-terrorism special forces raided houses in Sanaa and exchanged gunfire with suspected militants during a security sweep. He spoke anonymously according to regulations.

The United States considers Al-Qaeda in the Arabian Peninsula, the terror network’s offshoot in Yemen, to be its most dangerous branch.