Prosecutors say the defendants attempted to take over Istanbul's Sabiha Gokcen Airport on the night of July 15, when rogue elements in the army sought to bring down President Recep Tayyip Erdogan's government.

The hearing opened under tight security at a court complex in Silivri on the outskirts of Istanbul. Twenty-eight out of 62 suspects are being held under detention, the official Anadolu news agency reported.

Turkish authorities blamed followers of US-based Muslim preacher Fethullah Gulen for the putsch, which prompted a relentless purge of what the government calls the "virus" from state institutions. Gulen denies Ankara's accusations.

The suspects are facing life imprisonment on multiple charges, including use of force to try to destroy constitutional order, and "decapacitate" the Turkish parliament and the Turkish government, Anadolu reported.

If convicted, some of the suspects are also facing up to 15 years in prison for "voluntarily or deliberately aiding the group although they are not members of the armed terror organisation", it added.

The judge presiding over the case said some of the defendants were absent from Monday's hearing due to their presence in the Turkish army's operation into the Syrian town of Al-Bab, the private Dogan news agency reported.

Turkish authorities have suspended or sacked over 100,000 people in a crackdown on those with alleged links to coup plotters in the aftermath of the attempted coup.

Last week Erdogan said some 43,000 people had been arrested over suspected links to Gulen, with the first trials only now getting underway in the biggest legal process in the country's history.

A court in the eastern city of Erzurum on January 5 sentenced two army officers to life in jail over their roles in the failed coup, the first verdicts to be handed out.