Germany’s cybersecurity authorities have been criticised after it emerged they knew about a mass data attack on hundreds of politicians for weeks, but did not tell the police.

Journalists, celebrities and politicians, including Chancellor Angela Merkel, are among those whose personal data was published online.

The attacks took place throughout December, but did not become public knowledge until Friday.

It is unclear who was responsible.

The contacts, private chats and financial details of figures from every political party – except the far-right AfD – were posted on Twitter.

The interior ministry says there is no evidence that parliamentary or government systems have been compromised – and it is not clear whether the attack was the result of hacking – or someone with access leaking the data.

The Federal Office for Information Security (BSI) has come under fire after it emerged that they knew about the leak since December, while the Federal Crime Office was only notified on Friday, news agency DPA and newspaper Bild report.

BSI president Arne Schoenbohm told broadcaster Phoenix that his team “had already held corresponding talks very early in December with certain members of parliament who were affected”, and launched a “mobile incident response team”.

However, Dietmar Bartsch, parliamentary head of the left-wing Die Linke party, called the secrecy “completely unacceptable” and asked if the office had “something to hide”.

Meanwhile, lawmaker Andr√© Han said: “It makes me unbelievably cross that yet again I’ve found out about such things from the media – even though I’m a member of the parliamentary monitoring group… the federal government’s duty to keep parliament informed still applies between Christmas and the new year.”