The Turkish media had speculated for months that prosecutor Abdurrahman Yalcinkaya could again try to use laws banning anti-secular activity to close the governing party, and thereby prevent constitutional changes, which the senior judiciary deeply opposes.

Markets fell by almost one percent during Valcinkaya's press conference but rose by 1.5 percent when he failed to mention "a closure case against AK Party,” Halil Recber, a strategist at Anadolu Invest, said.

Turkish stocks closed at a fresh all-time high, as investors bought into Turkey's expected strong growth this year.

Turkey's secular establishment, made up of judges, generals and educators, fears the AK wants to reverse modern Turkey's secular values and Yalcinkaya was strongly critical of the constitutional changes.

"The proposed method of choosing members of the Constitutional Court and the Supreme Board of Judges and Prosecutors (HSYK) is undemocratic," Yalcinkaya said.

"The HSYK is being politicized by the reforms package... a new system that frees the judiciary from political interventions should be introduced." The AK, or Justice and Development Party, which denies having any Islamist agenda, submitted a wide-ranging draft reform package to parliament on March 30.

The government says the changes are needed to strengthen Turkey's democracy as it bids to join the European Union.

The reforms also would make it harder to ban political parties and make Turkey's traditionally powerful military answerable to civilian courts.

Critics say the changes would prevent the judiciary from providing checks and balances on government, as the superior court benches would be filled with AK nominees.

Prime Minister Tayyip Erdogan plans to put the reform package to a national referendum if the government fails to get a required two-thirds majority in a vote that is likely to take place in parliament later this month.

The party will seek a third consecutive term in an election due by mid-2011. But the political temperature has shot up since February when prosecutors began an investigation into an alleged coup conspiracy in 2003 and began detaining scores of retired and serving military officers.

The detentions also brought to light a struggle within the judiciary, as some judges ordered the officers' release, only to have other judges order them to be detained once more.

On Monday, the chief prosecutor of Istanbul replaced two junior prosecutors who had ordered the detention of around 90 officers in another sign of the internal conflict.