Germany's domestic intelligence agency warned Tuesday of cyberattacks by Russian state-linked hacker group APT28, which compromised vulnerable TP-Link internet routers to spy on military, government and critical infrastructure targets.

The Federal Office for the Protection of the Constitution said the warning was issued jointly with Germany's foreign intelligence agency and the U.S. FBI.

APT28, also known as "Fancy Bear", is attributed to Russia's military intelligence service, the GRU. The group attacked several thousand routers globally, including around 30 vulnerable devices in Germany.

In some cases, compromise was confirmed, prompting operators to replace affected routers. APT28 previously targeted Germany's parliament, the SPD political party and air traffic control authorities.