BERLIN — Twitter shut down an account on Friday that an unidentified hacker had been using for weeks to expose the personal details of several hundred German lawmakers in what appeared to be major privacy breach for the German political establishment.
It was not immediately clear who was behind the publication of the information, including personal emails, chats, identity cards and contact details. It was also not clear how the data was obtained, German officials said.
Links to sites hosting the material were posted on Twitter by an account named GOd. The breach appeared to target lawmakers from every major political party but one: the far-right Alternative for Germany, or AfD. Personal information from artists and journalists with leftist political leanings was also published.
Germans prize personal privacy — a legacy of abuses by the Nazi- and Communist-era secret police — and the country has long had some of the world’s strictest laws protecting personal information. Germany forced Google to allow individuals to blur images of their homes on its Street View mapping service, following outrage over the amount of data the company was collecting.
Beyond Germany, the hacking adds to concerns about the security of European parliamentary elections in May, which many officials fear are vulnerable to digital interference and disinformation campaigns by hackers or state-backed groups. Last month, European Union officials announced an action plan to better coordinate responses to false messages around the elections.
The information was released through links published on Twitter in the form of an Advent calendar, beginning on Dec. 1 with information about the German television comedian Jan Böhmermann, and ending with members of Chancellor Angela Merkel’s center-right party and its Bavarian counterpart. German news outlets reported the data breach late Thursday, and it was not immediately clear why it took more than a month to be discovered.
The Federal Office for Information Security called a crisis meeting on Friday to coordinate with the country’s domestic and foreign intelligence agencies in investigating the leaks. Based on an initial assessment, the office said, it did not appear that the main government computer network had been penetrated.
Martina Fietz, a spokeswoman for Ms. Merkel, said that it did not appear that sensitive information from the chancellery, or any of the chancellor’s personal data, had been leaked. German news outlets reported that Ms. Merkel and President Frank-Walter Steinmeier had been among those targeted.
Hours after news of the hacking broke, Twitter deleted the account that had been used to publish links to the information. The account supplied simple passwords that allowed anyone access to the data on various file-sharing platforms.
Jonas Kaiser, a Harvard University expert who studies online misinformation, said the weaponization of hacked information was becoming increasingly common in politics. The most notable example was emails from the Democratic National Committee during the 2016 election in the United States.
“A lot of leaks and hacking campaigns have become a more normal part of the political discourse,” he said.
Mr. Kaiser said the authorities would try to determine whether the attack was perpetrated by a state-backed group. The release of personal information by an individual or small group would get a different response than one by a government, he said.
A spokesman for the Left Party confirmed that the information of some of its members had been exposed, including Dietmar Bartsch, leader of its caucus in the lower house of Parliament.
Mr. Böhmermann, the first person targeted in the leak, sought several months ago to organize opposition to the far-right group Reconquista Germanica, which spreads disinformation and harasses, provokes and belittles opponents. The data, which included Mr. Böhmermann’s phone numbers, personal chats and photographs of his two young sons, was advertised as, “Nice things that you can have fun with.”
Germany’s main government network was breached by hackers in 2015, and the authorities worried that information obtained then would be used against politicians leading up to the 2017 election. Those fears were largely unfounded.
Hackers appeared to have again penetrated the German government’s main data network last March, however — a system that was supposed to be particularly secure and is used by the chancellor’s office, ministries and Parliament.