The voting system used by the Eurovision Song Contest was briefly forced offline after a suspected cyberattack caused an "extreme" surge in activity, reports Acumin.

During the final of the pre-qualification rounds which took place on Saturday, the Eurovision team noticed a a suspiciously heavy load on its voting servers putting the reliability of the system into question. The voting app was taken out of service as a result, with viewers informed by the hosts that earlier votes made using the service would be erased.

Eurovision has recently overhauled its voting system, with viewers asked to show their support for their chosen artist by casting 'heart votes' through a smartphone app. Users are able to use this system up to five times for each song, and the system has been credited with a 400 percent increase in voting over the previous year.

Speaking to SC Magazine, Christel Tholse Willers, head manager at Eurovision, said the app has had 738,000 downloads and 525,000 active users. Despite its popularity, though, the traffic on Saturday was deemed unlikely to be genuine.

“We are investigating an attack. The servers are configured for a very heavy load, but this was abnormal and extreme,” said Willers.

It is not known how the attack will affect the results of the song contest, but it is believed that the winner was so far ahead that the impact will be minimal. Eurovision also allows users to vote by other means, with more than 1.5 million votes cast via SMS and phone calls.

The security of the voting app was analyzed by Swedish security company Truesec before the final, which found that although it wouldn't be difficult to create fake votes, it would be difficult to do so in very high numbers.