ISTANBUL — The first group of more than 300 suspects accused of plotting to overthrow the Turkish government were sentenced Friday to up two decades behind bars, according to the country’s semi-official Anatolia news agency.

The former commander of Turkish air forces, navy and former commanders of the First Army, were handed 20-year sentences, the agency reported.

Six other generals and one former member of parliament from the National Movement Party were sentenced to 18 years in prison.

The alleged plot — widely referred to as Balyoz, or “Sledgehammer” in English — included 365 suspects and is thought to mark a dramatic reversal in the balance of political power in Turkey.

Dozens of military commanders — once considered untouchable in Turkish society — have been in prison for more than two years as the controversial trial has dragged on.

Defense attorneys have accused the country’s moderate Islamist government, as well as judges and prosecutors, of carrying out a political witch hunt.

“I am not expecting a fair decision,” said Huseyin Ersoz, a lawyer defending nine suspects in the case.

“It seems like the judges have already made their decisions. They push everything the defense shows aside and make their own decisions,” Ersoz said in a phone call with CNN from the Silivri Courthouse, where the trial is taking place. He said he has already applied to appeal the case before the European Court of Human Rights and the United Nations Human Rights Commission.

The Sledgehammer investigation has marked a dramatic setback for the once politically dominant Turkish armed forces, which have overthrown four governments in the last half-century.

The Sledgehammer trial has also signaled a key turning point in the ongoing power struggle between the country’s long-ruling secular elite and the Islamist-inspired elected government of Prime Minister Recep Tayyip Erdogan.