A Turkish court on Sunday remanded in custody seven serving soldiers accused over the interception last year of an alleged consignment of arms bound for Syria, state media said, according to AFP.
Following police raids in previous days, a total of 10 soldiers appeared before the Istanbul criminal court, the Anatolia news agency reported.
After hearings that lasted all day, three were allowed to go free while seven were arrested ahead of trial and will now be sent to prison.
They have been charged with membership of a terrorist group, impeding the work of the government and espionage.
The arrests are the latest in a string of detentions related to the stopping and searching of trucks in the southern provinces of Hatay and Adana near the Syrian border in January 2014 on suspicion of smuggling arms into Syria.
Documents circulated on the Internet claimed the seized trucks were Turkish National Intelligence Organization (MIT) vehicles delivering weapons to Syrian Islamist rebels fighting President Bashar Al-Assad.
Turkey has vehemently denied aiding Islamist rebels in Syria, such as the Islamic State (ISIS) group, although it wants to see Assad toppled.
The Turkish authorities have sought to link the affair to preacher Fethullah Gulen, currently residing in the United States, who President Recep Tayyip Erdogan accuses of running a parallel state through supporters in the judiciary and police with the aim of usurping him.
The government has imposed a full-blown media blackout, including on social networks, and the investigation is being carried out in the utmost secrecy, according to AFP.
Erdogan made a rare public reference to the case in a public speech in the city of Kayseri on Sunday, saying the searches of the trucks had been set up with the aim of "sending a message to the world" and it had been "treason".
Earlier this month, Turkey arrested the four prosecutors who had ordered the search of the trucks and they are now in prison ahead of trial.
Not including the latest arrests, the Anatolia agency said that a total of 47 people were being held in the investigation after a wave of detentions dating back to July 2014.
AFP contributed to this report.