BERLIN (AP) — Germany's dpa news agency reports that a Russian-backed hacker group has infiltrated the German government's secure computer networks.

Dpa cited unidentified security sources saying the group APT28 hacked into Germany's Foreign and Defense Ministries, and that it managed to steal data.

It reported Wednesday that the attack was noticed in December and may have lasted a year.

Officials at Germany's domestic intelligence agency, which is tasked with fending off hacking attacks, referred questions to the Interior Ministry. Officials there didn't immediately respond to a request for comment.

APT28, which has been linked to Russian military intelligence, has previously been identified as the likely source of an attack on the German Parliament in 2015, as well as on NATO and governments in eastern Europe.