BERLIN The German parliament, which was attacked by hackers in 2015, suffered an internet outage for several hours on Wednesday but there were no indications it was triggered by a cyber attack, a spokesman for the Bundestag said.
"At the moment there are no indications of a hack attack," said spokesman Ernst Hebeker.
He said internet and email functions on the Bundestag's servers went down at about 3:30 p.m. (1430 GMT). Experts believed the outage was the result of a technical problem and a replacement server was being installed.
Basic internet and email service was restored on Wednesday evening, parliamentary sources said, adding initial indications pointed to a major hardware failure rather than a cyber attack, but further investigation was needed.
"We're able to work again, but everything is not back to normal," said one of the sources.
The German parliament was hit by a cyber attack in 2015 that was blamed on APT 28, a hacking group experts say is linked to Russian military intelligence.
German intelligence agencies have warned there could be more cyber attacks ahead of national elections in September.
The agencies said in December they had seen a marked increase in Russian propaganda and disinformation campaigns aimed at destabilising German society, as well as targeted cyber attacks against political parties.
Allegations of Russian hacking soured the U.S. presidential election campaign last year and the U.S. Federal Bureau of Investigation is pursuing at least three separate investigations into the claims.
Arno Schoenbohm, president of the German Federal Office for Information Security Technology, warned in an interview with Der Spiegel on Wednesday that German political parties should improve their cyber security ahead of the elections.
"The parties are enormously important for our democracy, but they are small- and medium-sized businesses in which there is a lot of improvisation going on," Schoenbohm told the magazine.
"We need uniform laws about which equipment should be used and are calling for regular software updates and encryption."
(Reporting by Andreas Rinke and Andrea Shalal; Editing by David Clarke and Mark Potter)