Turkish authorities arrested the leaders of the main pro-Kurdish opposition party in a terrorism investigation yesterday.
Selahattin Demirtas and Figen Yuksekdag, co-leaders of the Peoples’ Democratic Party (HDP), were jailed pending trial after being held in overnight raids, officials said.
Ten other HDP lawmakers were also detained, although some were later released.
The United States expressed  concern, while Germany and Denmark summoned Turkish diplomats over the Kurdish detentions, and European Parliament President Martin Schulz said the actions “call into question the basis for the sustainable relationship between the EU and Turkey”.
Turkish Prime Minister Binali Yildirim told reporters: “Turkey is a nation of laws, nobody has preferential treatment before the law ... what’s been done is within the rule of law.”
The HDP lawmakers were arrested after they refused to give testimony in a probe linked to “terrorist propaganda”.
“Politics can’t be a shield for committing crimes,” Yildirim said.
Hours after the detentions, a car bomb planted by suspected Kurdish PKK militants killed nine people and wounded more than 100 near a police station in the southeastern city of Diyarbakir where some of the lawmakers were being held.
The HDP, which made history last year by becoming the first Kurdish party to win 10% of the vote and enter parliament, said that the detentions risked triggering civil war.
In a video message on a website close to the PKK, one of the militant group’s top commanders, Murat Karayilan, said the group would intensify its three-decade old armed struggle and called on Kurds, the country’s largest minority, to react.
Access was restricted to social media including Twitter, WhatsApp, YouTube and Facebook and a ban imposed on media coverage of the car bomb.
Asked about the measures, Yildirim said that access would return to normal “once the danger is removed”.
US State Department spokesman John Kirby said: “The United States is deeply concerned by the Turkish government’s detentions of opposition members of parliament ... and by government restrictions on Internet access today.”
He also condemned yesterday’s bombing and urged the PKK to “cease its senseless brutal attacks”.
European Union foreign policy chief Federica Mogherini raised her concerns in a telephone call with Turkey’s foreign and EU affairs ministers late yesterday.
German Foreign Minister Frank-Walter Steinmeier said Ankara had a right to fight terrorism but could not use it to justify gagging opponents.
Turkish Foreign Minister Mevlut Cavusoglu accused EU member states of supporting the PKK and dismissed the bloc’s criticism as “unacceptable”.
Turkey began negotiations to join the EU in 2005, but has made glacial progress, and there is no prospect of it joining anytime soon.
Southeastern Turkey has been rocked by political turmoil and violence for more than a year after the collapse of a ceasefire with the PKK, deemed a terrorist organisation by the United States and European Union as well as Turkey.
 President Recep Tayyip Erdogan and the ruling AK Party accuse the HDP of links to the PKK.
The HDP denies direct links and says it is working for a peaceful resolution of the Kurdish conflict.
The lira hit a new low against the dollar of 3.14 after the arrests, while the cost of insuring Turkish government debt against default hit its highest in over a month.
“I will not hesitate to be held accountable in front of a fair and impartial judiciary. There is nothing I cannot answer for,” the arrested Demirtas said in a statement to the prosecutor, which was shared by HDP lawmaker Besime Konca.
Police also raided and searched HDP’s head office in central Ankara.
Police cars and armed vehicles had closed the entrances to the street of the HDP headquarters.
A group of protesters chanting slogans tried to reach the party offices, but were stopped by police before they could enter the street, a Reuters witness said.
The HDP is the third-largest party in the 550-seat Turkish parliament, with 59 seats.
Parliamentarians in Turkey normally enjoy immunity from prosecution, but the immunity of many lawmakers, including HDP deputies, was lifted earlier this year.