Cairo: Egyptian prosecutors on Saturday slapped a fresh charge of "insulting the judicial authority" on ousted president Mohammed Morsi.
Morsi`s detention was extended by four more days pending investigation of the new charge.
"The investigative prosecutors accused Mohamed Morsi of insulting the judiciary by accusing 22 judges of forging parliamentary elections in 2005," official media reported.
In 2005, Morsi`s Muslim Brotherhood was a banned organisation but was allowed to field independent candidates for polls under then president Hosni Mubarak, who was toppled in 2011 following the Arab Spring uprising.
The 62-year-old is being held incommunicado since his ouster by the armed forces following protests on July 3.
Throughout his one-year rule, Morsi`s administration was at odds with the judiciary. The peak of the confrontation came in November 2012, when Morsi released an abrupt decree sacking the prosecutor general and immunising the Islamist-led Shura Council and Constituent Assembly from judicial dissolution.
On July 26, Morsi received his first 15-day detention order pending investigations into espionage and jailbreak charges.
He is accused of collaborating with Hamas to orchestrate his escape from Wadi El-Natroun Prison in early 2011, as well as destroying police records during the 2011 uprising.
In addition, he faces charges of espionage, and of attacking police stations with the intent to kill and abduct police officers and prisoners during the 2011 uprising.
Morsi, along with dozens of other members of the Muslim Brotherhood, escaped from prison during the 2011 revolution that toppled Mubarak.
The Palestinian Hamas and Lebanese Hezbollah groups have been accused of aiding the plot to attack prisons, resulting in the release of the inmates.
Most of the Brotherhood`s top leaders are currently detained on charges of inciting violence during recent or past clashes.
Over 1,000 people have died in a violent crackdown on Brotherhood supporters since the ouster of their leader Morsi in the popularly-backed coup.