ISTANBUL (AFP) - Turkeys military held a top-level meeting Tuesday to assess what it termed a 'serious situation as investigators grilled dozens of senior defence figures who were arrested over an alleged coup plot. All the generals and admirals of the Turkish military met in the headquarters of the chief of army staff to evaluate the serious situation, a statement said, without elaborating. In the most dramatic move to date against the armed forces, police detained more than 40 suspects Monday over a purported plan codenamed Operation Sledgehammer to topple the Islamist-rooted Justice and Development Party (AKP) administration, dating back to 2003. The suspects allegedly planned to bomb mosques and escalate tensions with Greece in a bid to force the downing of a Turkish jet, thus discrediting the government and forcing its downfall. Seventeen retired generals and four active-duty admirals were among those detained on charges of attempting to remove the government through force and violence and brought for questioning in Istanbul, reports said. Among them are the ex-air force chief Ibrahim Firtina, former navy chief Ozden Ornek and the former head of the Istanbul-based First Army, Cetin Dogan, who is accused of spearheading the plot. The generals were expected to be questioned by prosecutors on Wednesday before being brought before a judge to face possible charges, the Anatolia news agency reported. Operation Sledgehammer was exposed in January by the liberal Taraf newspaper which said the plan was discussed at a seminar in March 2003 and published transcripts of audiotapes that appeared to confirm some kind of anti-government action was considered at the gathering. The general staff-which has recently complained of a psychological smear campaign-has said the seminar involved the discussion of war-time contingency plans and denied any coup plot. Turkeys staunchly secularist army has traditionally wielded heavy political influence and unseated four governments since 1960, the last time in 1997 when it forced Islamist prime minister Necmettin Erbakan to resign. The AKP, which opponents accuse of secret ambitions to overthrow the secular system, was formed by moderates from Erbakans now-banned party. Turkeys two largest opposition parties slammed the government Tuesday over the latest arrests. Main opposition leader Deniz Baykal questioned why such an operation was mounted against retired generals watching TV at home in pyjamas and slippers over allegations dating back seven years. This is obviously a process of political score-settling, he said. Nationalist opposition leader Devlet Bahceli said the government was acting with hatred and feelings of revenge and called for early elections. Hugh Pope, a specialist on Turkey at the International Crisis Group think tank, expressed doubt there was a witch hunt against the army. The judiciary would certainly not have taken so many high-profile people into custody unless they had an absolute certainty in their mind that this is a real case, he said. Retired and active-duty soldiers are already among dozens of defendants on trial over the so-called Ergenekon network, which allegedly plotted to foment unrest to prompt a military coup. The investigation, underway since 2007, was initially hailed as a success, but its credibility waned with the arrest of academics, journalists and writers known as AKP critics. As suspects began accusing police of fabricating evidence, critics said the probe had become an instrument to bully the opposition and discredit the military, seen as the strongest bulwark of the secular system. In 2008, the AKP narrowly escaped being banned for violating Turkeys secular system.