BERLIN (Reuters) - Germany said on Wednesday hackers had breached its government computer network with an isolated attack that had been brought under control and which security officials were investigating.

A magnifying glass is held in front of a computer screen in this picture illustration taken in Berlin May 21, 2013. REUTERS/Pawel Kopczynski

A spokesman for the German Interior Ministry said the affected government agencies had taken appropriate measures to investigate the incident and protect data.

“The attack was isolated and brought under control within the federal administration,” which oversees government computer networks, he said in a statement, adding that the authorities were addressing the incident “with high priority and significant resources”.

The spokesman said he could give no further details immediately due to security and analysis measures that were still under way.

He did not comment on German media reports that the attack was launched by Russian hacker group APT28, which had already attacked the German parliament in 2015.

The reports said the group managed to steal data from the Foreign and Defence Ministries in the latest attack.

The ministry did not say when the attack took place. German media reported it happened in December.

German security sources said authorities had been aware of the incident for some time, but the Defence Ministry and the German military were not affected.

Jens Zimmermann, the Social Democrats’ (SPD) spokesman for digital issues, said the German parliament’s Digital Agenda committee had agreed unanimously to hold an extraordinary meeting, likely to be on Thursday.

“The federal government must inform parliament comprehensively,” he tweeted.

German Defence Minister Ursula von der Leyen declined to comment about the reports during an appearance in London.

News of the attack on German government computers comes after repeated warnings by German intelligence officials about possible meddling by Russia in last year’s federal election.

The head of the German domestic intelligence agency last year said such attacks had not occurred, but the risk of interference remained until a new government is in place.

Germany’s Social Democrats are voting by postal ballot on an agreement to form another “grand coalition” with Chancellor Angela Merkel’s conservatives, with the results to be made public on Sunday. If they reject the tie-up, Germany could face new elections or the formation of a minority government for the first time in its post-war history.

Western governments and security experts have linked the hacking group known as APT28 or Fancy Bear to a Russian spy agency, and have blamed it for operations including an attack on the Democratic National Committee ahead of the 2016 U.S. elections and the German lower house of parliament in 2015.

German officials have blamed APT28 for the May 2015 hack of the German lower house of parliament, the Bundestag, and other cyber attacks aimed at political groups, Merkel and other individuals, or institutions.

Moscow has previously denied in any way having been involved in cyber attacks on the German political establishment.

Top German intelligence officials have urged lawmakers to give them greater legal authority to “hack back” in the event of cyber attacks from foreign powers.