Lawyers for the families of protesters killed at an anti-regime rally last year filed charges on Saturday against several members of Yemen's former regime, including ousted strongman Ali Abdullah Saleh.
The charges against Saleh and other ex-regime members, among them his nephew Yehya Abdullah Saleh who still holds a senior post in the central security services, include "inciting and participating in the killing of young protesters" on March 18, 2011.
On one of the bloodiest days in the year-long uprising against Saleh's rule, gunmen described as the ousted leader's "thugs" sprayed bullets from rooftops around a square at Sanaa University, killing 52 people and wounding scores.
The attack sparked diplomatic scorn and condemnation from Western powers and human rights monitors.
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Lawyers in court on Saturday alleged that according to some eyewitness accounts, several attackers were driven to the site of the killings by cars bearing presidential number plates, an AFP reporter at the hearing said.
In addition to Saleh and his nephew, the charge sheet lists other top officials including former interior minister Motahar Rashad al-Masri and the former head of central security services, Abdulmalik al-Taieb.
The next hearing in the case is set to take place on November 23.
Hundreds of people were killed in Yemen's uprising that ended when Saleh agreed to step down in return for immunity for himself and his aides, based on a Gulf-brokered power transfer deal.
However, youth groups that have rejected the deal insist that Saleh and his former aides must be stripped of that immunity, and they still stage rallies demanding justice.