Russia reiterated its rejection of allegations that it hacked into German government computers, with a jibe from the Foreign Ministry on Thursday about World War II.

"We broke into the Bundestag only once, in 1945, while liberating Berlin from the Nazi scourge. At that time, it was called the Reichstag," Foreign Ministry spokeswoman Maria Zakharova told reporters.

"It is especially bewildering that Britain has added a hack of the Bundestag in 2015 to its growing list of claims" against Russia, Zakharova said, according to state news agency RIA Novosti.

Soviet forces stormed the Reichstag at the end of World War II in 1945, at times engaging in combat room by room. The Soviet Union lost more than 20 million people during the war, and the Allied victory remains a profound source of national pride in Russia.

Britain this month accused Russia of perpetrating a chemical weapon attack on a former Russian double agent in England, an accusation that Moscow has adamantly denied.

In solidarity with Britain, Germany and more than 20 other Western countries announced this week that they were expelling Russian diplomats.