CAIRO - Egyptian prosecutors Wednesday announced a new trial of ousted President Mohammed Morsi and the top leaders of his Muslim Brotherhood, accusing them of conspiring with Hamas, Hezbollah, Iran's Revolutionary Guard, and other groups to carry out a wave of terrorism to destabilize the country.

The charges, which carry a potential death penalty, are the heaviest accusations yet in a series of trials against the Brotherhood. The new trial of Morsi, the three top Brotherhood leaders, and 32 others appeared aimed at decisively crippling the top echelons of the group that dominated Egypt's political scene during Morsi's one-year presidency.

The timing appeared aimed at further tarnishing the Brotherhood ahead of a January referendum on a new constitution, a substantial rewrite of the charter largely drafted by Islamists under Morsi. The new military-backed government is seeking a strong yes vote for the constitution to show the legitimacy of the political transition process put in place after the military removed Morsi on July 3. Brotherhood supporters oppose the new document and have vowed protests against it.

Since the coup, prompted by huge protests calling for Morsi's removal, Egypt has been in continual unrest.

Throughout, the new government has depicted the Brotherhood as a violent movement that threatened the nation and forced the military to remove it from power. Previous, ongoing trials of Morsi and other Brotherhood leaders have focused on accusations the group is implicated in violence.

The new charges take that claim to a new level, accusing the group of being enmeshed with terrorists since 2005 in deals aimed at attaining and holding power, of plotting the collapse of police and prison breaks during the 2011 uprising that forced autocrat Hosni Mubarak out of power, and of organizing the Sinai extremist backlash.

Mohammed el-Damati, a defense lawyer for the Brotherhood, denounced the new trial - and those already started - as "political," aiming to give a legal veneer to the crackdown.

Rights lawyers, including some who believe Brotherhood members should be prosecuted for violence, have expressed similar worries that the wave of trials against them are mere political vengeance.

"The biggest victim now is justice and the truth," said Bahy Eddin Hassan, head of the Cairo Institute for Human Rights Studies, calling the new case part of the "ongoing contest" between the Brotherhood and the new government.

Morsi is already on trial on charges of inciting the murder of protesters against him while in office. After his ouster, Morsi spent four months in a secret military detention before he appeared in court to face the incitement charges in November. That trial resumes in January. Morsi's predecessor, Mubarak, is being tried over charges of failing to stop the killings of protesters during 2011 uprising.

The prosecutor's office did not announce a date for the new trial's start - but officials suggested it would come after the Jan. 14-15 referendum, fearing an earlier start would fuel turmoil.