About 135 Muslim extremists who spent more than a decade in Egyptian prisons have been released after signing statements renouncing violence, police said Monday.

The prisoners all belonged to al-Jihad, a group once headed by Al Qaeda's No. 2, Ayman Al-Zawahiri. Egypt began releasing them two weeks ago, police officials said on condition of anonymity because they were not authorized to speak to the media.

Al-Jihad and the al-Gamaa al-Islamiyya group were both were accused of participating in the 1981 assassination of President Anwar al-Sadat. Al-Zawahri was jailed for his involvement in the assassination, but was released in 1984. He left Egypt and helped form Al Qaeda with Usama bin Laden in the late 1990s.

Neither al-Jihad or al-Gamaa have been involved in attacks in Egypt since the 1990s.

Al-Gamaa first proposed a unilateral cease-fire in 1997 that went into effect in 1999. Most of its leaders, as well as hundreds of its members, have since been freed from prison.

Al-Jihad has long opposed reconsidering its radical views. But a few months ago, the group's jailed top ideologue, Sayed Imam Abdul-Aziz el-Sherif, led a review of al-Jihad's ideology and concluded it should unequivocally renounce violence.

El-Sherif, 57, left Egypt in 1986 to go to Afghanistan. He later wound up in Yemen where he was arrested in 2001 and handed over to Egypt in 2004. He is serving a life sentence and was not one of the militants released.

Hundreds, if not thousands, of militants from al-Jihad and al-Gamaa are still believed to be in prison, along with members of smaller networks. Egypt has never disclosed an official figure of militants or political inmates in its prisons.