Israel has previously refrained from openly taking sides in the conflict in order to preserve its relations with Russia.

According to the Washington Post, the leaked top secret documents also reveal that in February, senior leaders of the Mossad spy service called on the agency's officials and Israeli citizens to protest proposed judicial reforms to the new Israeli government, including several explicit calls to oppose the Israeli government.

According to the newspaper, the direct interference in Israeli politics by the Mossad, an external spy agency that is prevented from delving into internal affairs, is an important discovery.

Senior Israeli defence officials have denied these allegations.

The US Department of Justice has launched an investigation into the leaked documents, which were posted on social media over the past week.