Although the data does not appear to contain any politically sensitive information, it does contain personal details.
Hundreds of politicians in Germany, including Chancellor Angela Merkel, have had their data stolen and posted online according to reports.
Although the data does not appear to contain any politically sensitive information, it does contain personal details such as phone numbers, home addresses, and financial data.
According to the German newspaper Bild, which has retained copies of the leaked data, the whole of the German cabinet is affected – reaching as high as Mrs Merkel.
Germany’s President Frank-Walter Steinmeier is included in the breach, which also contains private party emails and business letters.
The data was posted through a Twitter account (@_0rbit) which has since been suspended, and was released in batches before Christmas.
According to a spokesperson for the country’s defensive cyber security agency, the BSI, Germany’s domestic and foreign intelligence agencies have met to co-ordinate their response.
It affected all of the political parties represented in parliament, except for the far-right Alternative for Germany party, according to public broadcaster RBB.
According to Katarina Barley, justice minister, the release is being treated as a “serious attack”.
She added: “The people behind this want to damage confidence in our democracy and institutions.”
In 2017, an attack on the computer systems of the Reichstag led to “a significant drain of data” according to the German police.
At the time, Holger Muench, head of Germany’s Federal Criminal Police Office, warned that the data could have been used to interfere in the country’s elections.
It is not currently known whether the 2017 attack is tied to the recent data dump.
Authorities have not publicly announced any suspects.