ISTANBUL - Twelve senior Turkish military officers were charged on Wednesday over an alleged plot to topple a government that secularist hardliners fear is pursuing a hidden Islamist agenda. Turkey's top military commanders, who have seen the army's role as ultimate guardian of secularism eroded under European Union-backed reforms, held an emergency meeting late on Tuesday and warned in a statement of a "serious situation". With tensions hitting investors' confidence and feeding speculation that elections due next year could be brought forward, Prime Minster Tayyip Erdogan and President Abdullah Gul will meet Turkey's top military commander on Thursday, a government source said. Turkish stocks closed down 3.4 percent and the lira weakened to a seven-month low against the dollar, while bond yields rose. Adding to uncertainty, Turkey's chief prosecutor Abdurrahman Yalcinkaya said he was looking into statements made by deputies from the ruling AK Party, but had not reached the stage of opening a formal investigation against the party. Yalcinkaya tried to have the party banned for anti-secular activities in 2008. Speculation that he could try again has prompted talk that the government could call a snap election. The AK Party, first elected in 2002 in a landslide victory over older, established parties blighted by corruption and accusations of misrule, is also embroiled in a dispute with the judiciary -- another pillar of the orthodox establishment. The military has ousted four governments of various political hues since 1960, although the army says the days of coups are now over.