Turkish prosecutors have indicted 196 people, including several former senior officers, over accusations they plotted a coup against the Islamist-rooted government, reports said on Monday.

According to the indictment cited by the Anatolia news agency, the plan was drawn up at the Istanbul base of the First Army shortly after the Justice and Development Party (AKP) came to power in November 2002.

First Army's former top general Cetin Dogan was singled out in the charge sheet as the chief suspect and the mastermind behind the alleged plan to oust the AKP, the offshoot of a banned Islamist movement that many accuse of undermining the country's secular order.

The coup plan was drawn up by Dogan on the grounds that "the Turkish state had begun to come under the influence of anti-secular and reactionary elements" after the election of the AKP, Anatolia quoted the indictment as saying.

Former navy chief admiral Ozden Ornek, former air force commander general Halil Ibrahim Firtina, and the former number two of the general staff, retired general Ergin Saygun, were also among those charged.

The Hurriyet newspaper reported on its website that there were more than 30 retired or serving soldiers among the suspects of the plot.

The indictment accuses all the defendants of "attempting to overthrow the government or prevent it from carrying out its duties through the use of force and violence", a crime punishable by 15 to 20 years in jail, Anatolia added.

The indictment said that the coup plot - codenamed "Operation Sledgehammer" - comprised several stages, the first of which was to "pave the way for a military takeover by plunging the country into chaos and unrest".

The plan called for the bombing of mosques in Istanbul and provoking tensions with Greece over the Aegean while using some media members to shape public opinion towards believing in the necessity of a military coup.

Once the coup was carried out, the military would place its own personnel in key government and state institutions before setting up a national consensus government that would eventually hold elections, according to the indictment.

The coup plot was first reported in January by the Taraf newspaper, which routinely targets the army. The daily said it had obtained documents and audio tapes indicating that a coup plan was drawn up and discussed at the First Army.

Dogan has denied the charges, claiming that papers from a contingency plan based on a scenario of domestic unrest had been doctored to look like a coup plot.

The investigation - the toughest action so far against the influential army - initially saw the arrest of dozens of retired and serving soldiers pending trial as part of the probe.

But they were all subsequently released amid accusations that prosecutors had issued arrest rulings liberally and were effectively punishing suspects before the charges had been proven in court.

Opponents have accused the government of using the investigation to discredit the army, the guardians of the country's strictly secular order.

They argue that the AKP wants to remove a major obstacle in its plan to raise the profile of Islam in the country.

The government categorically denies charges that it has designs against the secular order and has described the probe as a step towards improving democracy.

The once-untouchable Turkish army, which has ousted four governments since 1960, has seen its influence wane in recent years under EU-inspired reforms.