Istanbul's chief prosecutor has said 86 people have been indicted
Police in Turkey have arrested a further 20 people over a suspected plot to overthrow the government, according to Turkish media reports.
The arrests are part of an ongoing investigation into a shadowy ultra-nationalist group known as Ergenekon.
Eighty-six people have already been charged with involvement in the group.
The latest arrests took place in five provinces around the country, according to the Anatolia news agency, including 12 people in Konya province.
Other arrests took place in Istanbul, neighbouring Kocaeli, the eastern province of Elazig and Mersin, on the Mediterranean coast.
Among those detained were three senior members of a small leftist party and a journalist.
The indictment announced earlier this month against the 86 suspects includes charges of creating an "armed terrorist organisation", attempting to use violence to oust the government and fomenting an armed rebellion.
Another 21 people were arrested this month as part of the same probe, including two retired high-ranking military generals.
The police investigation against Ergenekon was launched in June 2007 after explosives were found in a house in Istanbul.
Prosecutors say the group is behind a series of violent acts including the bombing of a secular newspaper and an armed attack on a court - attacks they say were designed to provoke a response by nationalists, and a coup by the army.
But the opposition says that the arrests are political retaliation for a case brought against Turkey's governing AK Party.
The AK Party risks being outlawed if the constitutional court decides it is violating the country's secular constitution by trying to impose Sharia law in Turkey, a claim denied by the party.