Turkish authorities have formally arrested 1,656 people in the past six months for allegedly supporting terrorist organisations or insulting officials on social media, and are investigating at least 10,000 others, the Interior Ministry said Saturday.

In a statement it said legal action had been taken against 3,710 people identified by police.

Beside those arrested, 1,203 people were released on probation, 767 were released and 84 others are still in detention.

Charges include provoking hatred among the people; praising terrorist organisations; disseminating terrorist propaganda; openly declaring allegiance to terrorist groups; insulting statesmen; and targeting the indivisibility of the state or safety of citizens.

Investigations and legal procedures are underway against an additional 10,000 people reported to public prosecutors.

Turkey declared a state of emergency soon after a failed coup in July, detaining thousands of citizens and purging tens of thousands of public servants over alleged ties to outlawed groups.

Western governments, human rights group and legal experts have repeatedly expressed concern over the crackdown, which some say has begun targeting political opponents and critics. Ankara defends its actions saying they are necessary precautions in the face of ongoing nationwide terrorism.

This year Turkey has seen a series of attacks and bombings in major cities that were the work of either the Islamic State group or Kurdish militants.

Turkey frequently restricts access to social media websites to prevent the spread of graphic images and other material authorities say would harm public order or security.

Such restrictions usually follow a major crackdown or a terrorist attack. On Friday access was restricted to social media websites for several hours after the Islamic State group released a video purportedly showing two Turkish soldiers being burned alive.