Berlin -- Data and documents belonging to hundreds of German politicians have been hacked and posted online via Twitter, a German broadcaster reported Friday. The leak, which saw the data posted in daily batches before Christmas on a Twitter account that has been active since mid-2017, affects all parties in parliament except the far-right Alternative for Germany, public broadcaster RBB reported.

It said there appeared to be no system to what was posted. Although it reportedly includes personal information such as cellphone numbers, addresses, internal party communications and in some cases bills and credit card details - some of the data years old - there seem to be no politically sensitive documents.

Germany's daily newspaper Bild reported Friday, citing sources in the national security agency, that the government's secure internal computer network was not affected by the breach. The security source told Bild that the government's networks were not fending off any sustained attack.

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A Defense Ministry official told the Reuters news agency that Germany's military networks also remained unaffected by the hack.

There was no immediate information on who was responsible or on the source or sources of the data, and whether they were all authentic. News agency dpa reported that the information included a fax number and email address belonging to Chancellor Angela Merkel and several letters to and from Merkel.

German Chancellor Angela Merkel, center left in red, leads the last cabinet meeting of the German government for this year, at the chancellery in Berlin, Dec. 19, 2018. AP

Alexander Dobrindt, the conservative Christian Social Union's top lawmaker in Berlin, said that authorities were working to establish "what data are affected and to what extent."

The data breach hit politicians at all levels - including the European, German and state parliaments as well as those on city governments, said Martina Fietz, a spokeswoman for Chancellor Merkel.

"The German government takes this incident very seriously," she said Friday, adding that the country's cyber-defense center was investigating the breach.