(Refiles to change day of vote and name of Parliament spokesman)
BRUSSELS (Reuters) - A pro-Kremlin group has claimed responsibility for a denial of service attack on the European Parliament website after its lawmakers designated Russia a state sponsor of terrorism, the president of the institution said on Wednesday.
"The European Parliament is under a sophisticated cyberattack. A pro-Kremlin group has claimed responsibility," Roberta Metsola said in a tweet.
"Our IT experts are pushing back against it & protecting our systems. This, after we proclaimed Russia as a State-sponsor of terrorism. My response: SlavaUkraini (glory to Ukraine)", she said.
Earlier on Wednesday, lawmakers voted to declare Russia a state sponsor of terrorism, arguing Moscow's military strikes on civilian targets such as energy infrastructure, hospitals, schools and shelters violated international law.
The move is largely symbolic, as the European Union does not have a legal framework in place to back it up. At the same time, the bloc has already imposed unprecedented sanctions on Russia over its invasion of Ukraine.
"The availability of @Europarl_EN website is currently impacted from outside due to high levels of external network traffic. This traffic is related to a DDOS attack (Distributed Denial of Service) event," Parliament spokesman Jaume Duch said in a tweet.
Distributed denial of service (DDoS) attacks work by directing high volumes of internet traffic towards targeted servers in a relatively unsophisticated bid by so-called "hacktivists" to knock them offline.
(This story has been refiled to change the day of vote and the name of Parliament spokesman)
(Reporting by Bart Meijer, Sabine Siebold and James Pearson; editing by Foo Yun Chee)