The Istanbul prosecutor's office has launched an investigation of newspaper editor following the publication of images of truckloads of ammunition, which the paper says proved that a convoy which was stopped on its way to Syria on a Turkish intelligence mission was carrying arms to rebels.

The state-run Anadolu Agency said Friday that Can Dundar, chief editor of the Cumhuriyet daily, was under investigation for possible breach of anti-terrorism laws.

The newspaper says the photographs showed an incident in January 2014 when local authorities stopped the convoy for searches, touching off a standoff with intelligence officials.

Government officials insisted the convoy contained humanitarian aid. They said the searches were part of a conspiracy by U.S.-based cleric Fetullah Gulen to destabilize the government.

Officials who ordered the search were arrested recently.