The presiding judge at the trial of ex-Ivorian leader Laurent Gbagbo on Monday apologised for a major blunder last week in which the names of several protected witnesses were accidentally revealed.
"First of all the court as such has to apologise. I think this is the fair thing to do," judge Cuno Tarfusser told an open hearing of the International Criminal Court (ICC) at the start of the second full week of Gbagbo's crimes against humanity trial.
A visibly annoyed Tarfusser said "what happened is really incredible".
Friday's incident, when the prosecutor blurted out the names of several protected witnesses thinking the microphones were off, was "of the utmost gravity," Tarfusser added.
After the apology, the three-judge bench then met behind closed doors with the prosecution to decide what to do next.
War crimes prosecutors opened their case in the trial of Gbagbo, 70, and his firebrand youth militia leader Charles Ble Goude, 44, on January 28.
The two men have denied four charges arising out of their alleged roles in post-election violence that ravaged the west African country in 2010-11.
But on Friday four top prosecution witnesses were outed when the microphones were left on during a closed session in the high-stakes trial.
A clip in which prosecutor Eric MacDonald can be clearly heard giving the names of the witnesses has been widely circulated on social media, including on YouTube, since Friday.
The blunder made headline news in the Ivory Coast and has provoked outrage from Gbagbo's supporters and from his bitter rival, Ivorian President Alassane Ouattara over the weekend.
Protecting witnesses is one of the key efforts of the ICC as it seeks to bring to justice those behind some of the world's worst crimes.
The ICC goes to enormous lengths to shield the identity of sensitive witnesses from the public, pixellating their faces and disguising their voices.
Friday's incident however was not the first in the trial.
On Wednesday, the prosecution's first witness, P547, accidentally gave his name as he recounted how forces loyal to Gbagbo allegedly fired on unarmed protesters.
Some 3,000 people were killed after the disputed Ivory Coast presidential vote in late 2010, when Gbagbo refused to cede victory to Ouattara, who was backed by international powers after snatching a narrow victory.