Turkey's main opposition party has started a 250-mile march from the capital to an Istanbul jail in protest over the imprisonment of one of its politicians.
The leader of the pro-secular Republican People's Party, Kemal Kilicdaroglu, called the "march for justice" after parliamentarian Enis Berberoglu was convicted to 25 years in prison for revealing state secrets.
Thousands of people set off on the march from Ankara, led by Mr Kilicdaroglu carrying a banner reading "Justice".
Mr Kilicdaroglu said he wants justice, democracy and freedom in Turkey.
"Let the whole world hear, we are facing a dictatorial regime in Turkey, in our own land," he said.
On Wednesday, an Istanbul court found Berberoglu, a former journalist, guilty on espionage charges.
His case stems from a 2015 story by the Cumhuriyet newspaper suggesting Turkey's intelligence service had smuggled weapons to Islamist rebels in Syria.
Berberoglu was accused of giving journalists footage that showed local authorities searching Syria-bound trucks allegedly carrying mortar rounds and getting into a stand-off with Turkish intelligence officials.
Turkish leaders denied supporting Islamic rebels and said the trucks contained aid for Turkmens in Syria.
Can Dundar, Cumhuriyet's then editor-in-chief, who is now abroad, and the paper's Ankara representative, Erdem Gul, are also on trial on similar charges.
Separately, the three are being tried for "aiding a terror organisation without being members", referring to the network of US-based cleric Fethullah Gulen, who is accused of orchestrating last summer's bloody coup.
The prosecutor believes Mr Gulen's network to be the source of the leaked images.
After the verdict, Mr Kilicdaroglu tweeted: "In this country, the punishment for covering the news of a truck filled with weapons heading to terror groups is 25 years in prison but illegal arm shipments are allowed!"
Berberoglu is the first politician from the Republican People's Party to be imprisoned since a constitutional amendment stripped parliamentary immunities last year.
A dozen pro-Kurdish politicians are already in prison for allegedly supporting terror and more than 50,000 people have been arrested for purported links to Mr Gulen.
Turkish media said the march would take two weeks, covering approximately 12 miles each day. Mr Kilicdaroglu is being escorted by his security detail.