A Turkish court has ordered a retrial for four Kurdish former MPs, who were freed after a decade of imprisonment.
The four were released from prison in June
The court said the four did not receive a fair hearing at their original trial in 1994 when they faced charges of collaborating with Kurdish rebels.
It also overturned the convictions of the four - who include award-winning rights activist Leyla Zana.
The release of the four last month was welcomed by the European Union and human rights groups.
Ms Zana, Orhan Dogan, Hatip Dicle and Selim Sadak were jailed for their alleged ties to the now-defunct Kurdistan Workers Party (PKK), which advocated a violent campaign for Kurdish self-rule.
Defence lawyer Hamit Geylani welcomed the appeal court ruling saying: "The political, anti-democratic verdict which fell foul of justice and law has been overturned."
No date has yet been set for the new trial.
Earlier this week, police pressed for new charges to be brought against the four for making separatist speeches at rallies in south-eastern Turkey last month.
They were also accused of speaking Kurdish at the rally, in violation of Turkish law.
Most restrictions on the use of the Kurdish language in Turkey have been lifted in recent years, but speeches in Kurdish are still forbidden under Turkish laws governing elections and political parties.
Ms Zana has become a symbol of both Kurdish resistance and Turkey's flawed judicial process since she was sent to jail.
She and her colleagues were retried in 2003, but observers said the retrial also suffered major procedural flaws.
The BBC's Jonny Dymond, in Istanbul, says there are hopes that the third trial the four now face will be different.
They will not be kept in prison during the trial and the strong presumption is that given the reforms to Turkey's courts over the past few years, they will have a better chance of presenting their case, he says.
The retrial has an important symbolic value as Turkey is keen to show the European Union that it is fit to start membership negotiations.
Our correspondent says an open trial which is demonstrably fair would go a long way towards assuaging European concerns about Turkey's treatment of both its Kurdish minority and also those who face its judicial system.