The swoop against the paper raised fresh concerns over declining media freedoms in Turkey, a key European Union ally, ahead of a visit by Prime Minister Ahmet Davutoglu to Brussels Monday for a crucial summit meeting with EU leaders.
"Free press cannot be silenced," a group of demonstrators including the paper's readers shouted outside the Istanbul premises of Zaman daily, staunchly opposed to President Recep Tayyip Erdogan.
Police used large amounts of tear gas, water cannon and plastic bullets to disperse around 500 people clapping in protest, an AFP photographer at the scene reported.
Turkey's top-selling Zaman newspaper, closely linked to Erdogan's arch-foe the US-based preacher Fethullah Gulen, was ordered into administration by the court on the request of Istanbul prosecutors, local media reported.
Also Read
Zaman published a defiant edition today warning of the "darkest days" in the history of the press.
"The Constitution is suspended," it said on its front page in large font on a black background.
Sevgi Akarcesme, the editor-in-chief of the paper's English language edition Today's Zaman, said on Twitter today that "All internet connection is cut off at the seized #zaman building by police raid."
"We are not able to work anymore," she wrote.
Before midnight yesterday, a team of police arrived with water cannon trucks and advanced military style towards the waiting supporters, firing freezing water directly at them.
Using bolt-cutters to unlock the iron gate in front of the building, dozens of police then marched into the premises to seize the headquarters and formally place it under administration, pushing aside anyone who stood in their way, media images showed.