BERLIN - The continuation of a widely-publicized cyber attack on the IT systems of the German federal government cannot be ruled out entirely, a spokesperson for the interior ministry told press on Friday.

Local media reported on Thursday that Germany's federal government had experienced a serious and sustained attack on its data networks that could have begun as early as December 2016 and lasted until Wednesday.

In response, Ole Schroeder, the parliamentary state secretary at the interior ministry, told RedaktionsNetzwerk Deutschland (RND) that the situation was under control by German security authorities.

But on Friday, when questioned whether it was possible that the attack was still ongoing, the spokesperson said he could not provide a definitive "yes or no" answer. Such a statement of absolute fact would imply a "level of insight" which would "never be achieved in this context."

Similarly, the spokesperson said that it was impossible to determine the exact extent of the hacking incidents.

German Interior Minister Thomas de Maiziere took the strategic, but controversial, decision to allow the hackers to continue their hacking attempts after they were first discovered without informing the public. The interior ministry defended this choice by saying it had taken appropriate counter measures to prevent any harm to the federal government and wider citizenry.

But members of the parliamentary committee which supervises national intelligence agencies in Germany were critical on Thursday that they had been informed too late about the incident.

Citing security circles, the newspaper Tagesspiegel reported that the cyber attack had now been stopped. However, media reports of the incident forced intelligence agencies to end their monitoring measures, which hampered investigations.