Some Turks believe their government is a threat to secular values
A top Turkish prosecutor has brought charges against 86 people allegedly involved in a coup plot.
Aykut Cengiz Engin said those charged included leading figures from the army, business and the secular press.
The charges follow speculation about a shadowy group of hardline nationalists determined to act in what they see as defence of Turkey's secular values.
Tensions have been rising in Turkey amid efforts to close the ruling party over alleged anti-secular activities.
The Constitutional Court is considering a case against the AK Party, in which it is accused of aiming to introduce Sharia law in Turkey, in contravention of the strictly secular constitution.
The Turkish prime minister and president - both AKP members - are named in that case and could be barred from office. They and the party reject the charges, which they say are part of a campaign against the party.
On Monday prosecutor Mr Engin filed charges at an Istanbul court against 86 people, 48 of whom are already in custody.
In the current highly-charged political atmosphere, many think it is no coincidence the two cases are running in tandem
"The indictment covers crimes such as forming an armed terror group... and attempting to overthrow the government by force," Mr Engin said.
A court must decide within two weeks whether to open the case against the 86 suspects.
They are accused of plotting to create chaos in Turkey, provoking secularist anger and a military coup that would topple the government.
The indictment referred to the killing of a judge in a 2006 armed attack on a court, and the bombing of a secularist newspaper.
There have been several coups by the Turkish military, which sees itself as the ultimate guardian of the country's secular values.
Some secularists believe the AK Party, many of whose members are former Islamists, is intent on installing Islamism in Turkey. They say the AKP's moves to overturn a ban on the Islamic headscarf at universities is evidence of this.
'Deep state' network
Prosecutor on the indictment against the alleged plotters
Dozens of suspects have been arrested over the past year, following the discovery of a cache of hand grenades at the house of a retired army officer.
Prime Minister Recep Tayyip Erdogan has promised to crack down on the so-called Ergenekon group - an alleged "deep state" network of renegade ultra-nationalists from the military, police, business and press.
Prosecutor Engin said the 86 charged on Monday include at least one former general, along with journalists, academicians and businessmen.
He said an additional indictment was being prepared against a dozen others, including two senior retired generals arrested earlier this month.
Critics of the government accuse it of using the investigation to suppress some of its most vocal opponents.
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