CAIRO, Dec 20 (Reuters) - Egypt's chief public prosecutor, who stepped down this week in the face of protests from judges who said his appointment was an assault on their independence, said on Thursday he had retracted his resignation.

Public Prosecutor Talaat Ibrahim, first appointed by President Mohamed Mursi last month, said he had changed his mind because his resignation on Monday had been offered under duress, according to comments carried by the state-run al-Ahram news website.

Ibrahim resigned after more than 1,000 members of his staff gathered in front of his office in Cairo to demand that he step down.

The protesting prosecutors said Mursi's decision to appoint Ibrahim, instead of the leaving the appointment to judicial authorities, threatens the independence of the judiciary.

Ibrahim, describing his removal from office as "mysterious and abnormal", said it was unprecedented for a chief prosecutor to be forced to quit by his staff.

He said it was now up to the justice minister to decide whether to accept his resignation.

A number of prosecutors immediately announced they were suspending work and would stage an open-ended protest outside Ibrahim's office.