A Turkish court was due on Monday to deliver its first ruling in the trial of 275 people including a former army chief accused of plotting to overthrow the country's Islamic-rooted government.
Among the defendants in the high-profile case -- seen as a key test in Prime Minister Recep Tayyip Erdogan's showdown with secularist and military opponents -- are ex-military chief Ilker Basbug and other army officers as well as lawyers, academics and journalists.
They face dozens of charges, ranging from membership of an underground "terrorist organisation" dubbed Ergenekon to arson, illegal weapons possession, and instigating an armed uprising against Erdogan and his Justice and Development Party (AKP), which came to power in 2002.
The 2,455-page indictment accuses members of Ergenekon -- an alleged shadowy network of ultranationalists trying to seize control in Turkey -- of a string of attacks and political violence over several decades to stir up unrest.
Turkey's secular opposition has denounced the lengthy trial, which began in 2008, as a witch hunt aimed at silencing government critics.
Pro-government circles have praised the Ergenekon trial as a step towards democracy in Turkey, where the army violently overthrew three governments in 1960, 1971 and 1980.
In 1997, the army pressured then Islamic-leaning prime minister Necmettin Erbakan, the political mentor of the current premier, into stepping down in what was popularly dubbed a "post-modern coup" strategy.
Thousands of supporters of the defendants were expected to turn out on Monday at the court, where Turkish authorities have stepped up security, doubling the number of metal barriers in case of unrest.
On Friday, Istanbul governor Huseyin Avni Mutlu said a planned demonstration in front of the court house would not be allowed and would be deemed "illegal."
"Do not come ... in vain," he told potential protesters.
Mutlu said that only lawmakers, lawyers, suspects and members of the press would be allowed to follow the hearing inside the courtroom.
Prosecutors claim that Ergenekon, named after a mythical place in central Asia believed to be the homeland of Turks, is made up of loosely connected branches with an eventual goal of toppling the AKP government and restructuring Turkey on a nationalist footing.
The network was uncovered in June 2007 when weapons and explosives were discovered during an anti-terrorist operation in an Istanbul suburb.
The trial is one of a series of cases in which members of the Turkish army, the second biggest in NATO, have faced prosecution for alleged coup plots against an elected government.
In a separate case in September dubbed "Sledgehammer," more than 300 hundred active and retired army officers, including three former generals, received prison sentences of up to 20 years over a 2003 military exercise alleged to have been an undercover coup plot.