Protests at next week's G20 summit in Hamburg, Germany, could also come from all over the internet.

And that's what's worrying Germany's top cybersecurity officials. Dozens of experts will stand by at a 24/7 command center among the 20,000 police with dogs, horses and helicopters there to deal with potential physical violence from the expected tens of thousands of protesters, reports Reuters.

"As the national cybersecurity agency ... we're concerned about everything from (persistent threats) to groups like Anonymous and Lulzsec that could be planning political protests using cyberattacks," said Arne Schoenbohm, president of Germany's Federal office for Information Security, in an interview with the news agency.

Besides political protests from hacker groups, Schoenbohm is also concerned about attacks from cells linked to foreign governments, including Russia, which have been targeting Germany's political parties and think tanks ahead of the country's national elections in September.

It's not the first time such attacks and attempts by hacker groups linked to Russia have taken place. The US elections were meddled with, and more recently, Russian hackers appeared to have targeted campaign staff of French president Emmanuel Macron with phishing attacks.