Turkish prosecutors are preparing to open criminal procedures against nearly one hundred academics and intellectuals living Germany, German media NDR, WDR and Süddeutsche Zeitung reported on Sunday.

The Turkish academics, some of whom have already received legal notices, will be charged with "making propaganda for a terrorist organization," the media outlets reported.

Read more: Turkish academics win Aachen Peace Prize.

In early 2016, 1,128 Turkish and international scholars signed an open petition, "We will not be party to this crime," condemning Turkish security forces' operations against the armed Kurdistan Workers' Party (PKK) youth wing in dozens of cities in the predominately Kurdish populated southeast.

A photo from February 2016 shows widespread destruction in Cizre after months of fighting and curfews.

Known as "Academics for Peace," the group called for an end to "deliberate and planned massacre," open-ended curfews and human rights abuses committed during months of security operations in 2015 and 2016. They also demanded the resumption of peace talks with the PKK.

Hundreds of security forces, PKK militants and civilians were killed in months of military operations that destroyed several towns. Hundreds of thousands of civilians were displaced. More than two years on, security operations continue and some towns face curfews.

Read more: Families in Turkey's southeast continue to suffer

Erdogan targets Turkish citizens abroad

A number of academics are already on trial in Turkey and several hundred more lost their jobs for signing the petition. About 100 of the signatories fled to Germany, where some took up academic positions.

Turkish President Recep Tayyip Erdogan unleashed a torrent of accusations against the academics at the time, deeming them terrorists and demanding punishment.

More than one hundred academics in Turkey have already received identical indictments. Now more are being sent out to Turkish academics living in Germany.

The indictments relate to alleged crimes tied to the publication of the petition, not engaging in violence, according those seen by NDR, WDR and Süddeutsche Zeitung.

Istanbul's top prosecutor accuses the signatories through their words of intending to present the Turkish state as an "illegitimate, destructive force" and legitimizing the violence of the PKK. Making terrorism propaganda carries up to a seven-and-a-half-year sentence in Turkey.

A protester holds a sign reading "We demand peace" at a demonstration in front the Istanbul courthouse where four academics went on trial last year for signing the petition.

Further storm ahead for Turkey-German ties

The signatories living in Germany face little prospect of being extradited, but would face arrest if they returned to Turkey.

The indictments are likely to further strain already frayed ties between Turkey and Germany over a massive crackdown following last July's failed coup attempt.

More than 50,000 people have been arrested and some 150,000 dismissed from their jobs under a state of emergency. The government has used the emergency powers to replace more than 80 elected Kurdish mayors with appointees.

Among those arrested in the purges are about a dozen Turkish-German nationals.

From January to September this year, more than 5,000 Turkish nationals have sought asylum in Germany. Hundreds of them are acemedics, senior officials and military officers.