Ukraine says evidence points to Russia being behind cyber-attack

Claim comes as Microsoft warns hack that hit government websites could be worse than first feared

Ukraine has said it has evidence" Russia was behind a massive cyber-attack that knocked out key government websites last week, while Microsoft warned the hack could be far worse than first thought.

Tensions are at an all-time high between Ukraine and Russia, which Kyiv accuses of having massed troops on its border before a possible invasion. Some analysts fear the cyber-attack could be the prelude to a military attack.