ISTANBUL (Reuters) - Turkish authorities released eight people who were detained on Friday under an investigation into jailed rights activist Osman Kavala and accused of following him in a bid to unseat the government through mass protests in 2013, their lawyers said.

Police have said the 13 people detained on Friday, including two prominent academics, were accused of working with Kavala to incite the May 2013 unrest, which began as demonstrations against urban development plans at Istanbul’s Gezi Park but later turned into nationwide anti-government protests.

Lawyers for the detainees told Reuters on Saturday that six had been released after being questioned by the police late on Friday and another two were released on Saturday, but all were banned from travel.

Three people were still giving testimonies to the police and another two were sent to the court on arrest orders, they said.

Among those released were Turgut Tarhanli, dean of Istanbul Bilgi University’s law faculty, Betul Tanbay of the Bogazici University, who was elected this year as vice president of the European Mathematical Society, and staff members of Kavala’s Anadolu Kultur organization, the lawyers said.

Turkish police did not immediately respond to a Reuters request for comment.

Kavala, a well-known civil society leader, was jailed a year ago pending trial for trying to overthrow the government, in a process authorities say started with the Gezi demonstrations and culminated with an attempted coup in July 2016.

At the time, the Gezi demonstrations, in which at least 10 people died and thousands were injured in a government crackdown, were the biggest ever staged against the government of Tayyip Erdogan, now president, then entering his second decade as prime minister.

Human rights groups and European Parliament members have repeatedly called on NATO member Turkey to release Kavala. An indictment against him has not been issued.

The European Union and the United States have also called for the release of the detainees.

Since a July 2016 attempted putsch, Turkey has jailed 77,000 people as they face trial, suspending or dismissing some 150,000 civil servants and military personnel and shutting down dozens of media outlets.

Police still frequently carry out operations targeting the network of U.S.-based cleric Fethullah Gulen, whom Ankara accuses of orchestrating the abortive coup.