BERLIN (Reuters) - Chancellor Angela Merkel’s junior coalition partners, the Social Democrats (SPD), demanded on Sunday that her interior minister quickly find out what Germany’s security agencies knew about a huge data breach and how they reacted.

FILE PHOTO: Lars Klingbeil of the Social Democratic Party (SPD) arrives for coalition talks at the Christian Democratic Union (CDU) headquarters in Berlin, Germany, February 6, 2018. REUTERS/Hannibal Hanschke

The breach has shocked Germany’s establishment and risks rocking Merkel’s awkward ‘grand coalition’ again just months after a row over the fate of the domestic intelligence agency chief came close to tearing apart the ruling alliance.

The government said on Friday that personal data and documents from hundreds of German politicians and public figures including Merkel had been published online, in what appeared to be one of Germany’s biggest data breaches.

Lars Klingbeil, secretary general of the center-left (SPD), told the Funke media group the government must quickly shed light on “which agencies knew what exactly when, and how that was dealt with”.

“This should be a priority for (Interior Minister) Horst Seehofer. It’s about protecting our democracy,” Klingbeil added.

Seehofer told the Sueddeutsche Zeitung he only became aware of the breach on Friday morning, but that he would share everything he finds out with the public and intended to do so by the middle of this week at the latest.

The ecologist Greens leader in parliament, Anton Hofreiter, said the president of the BSI cyber defense agency, Arne Schoenbohm, must explain himself urgently in an extraordinary parliamentary committee meeting.

The BSI on Saturday defended its role in responding to the data breach, saying it could not have connected individual cases it was aware of last year until the entire data release became public last week.

Last year, Seehofer was at the center of a political storm over another security agency chief, whose the fate almost tore apart Merkel’s coalition of her conservative bloc and the SPD.

Despite SPD resistance, Seehofer rescued Hans-Georg Maassen from dismissal in September when the domestic spy chief questioned the authenticity of videos showing far-right nationalists chasing immigrants in the eastern city of Chemnitz.

But Maassen was subsequently sacked in November over a speech given behind closed doors condemning “naive and leftist” government policies.