Leonid Volkov, a close ally of jailed Russian opposition leader Alexei Navalny who was attacked outside his home in Lithuania, has vowed to "never give up" fighting against Russian President Vladimir Putin, whom he called the "biggest threat to the world in the last 80 years". In his first television interview since he was struck with a hammer outside his home on the outskirts of Vilnius, Volkov told the BBC he would continue to fight to ensure that the "ultimate sacrifice" of Navalny, who died in a penal colony after three years in detention, "was not in vain". "We always understood that we are fighting against a crazy, fascist dictator who does not recognise any red lines," said the opposition politician, adding that Navalny's death was "an open wound in our hearts". "If there are 50 things we can do, we have to do all 50. If we do 49, it's not enough, because this is the biggest threat to the world we have seen in the last 80 years," said Volkov, who called for "military, economic, political, internal, external" pressure on the Russian president. Volkov, 43, was hospitalised after he was attacked outside his home in early March, and Lithuanian authorities have detained three suspects. "A man attacked me in the yard and hit me in the leg about 15 times. The leg is fine. It hurts to walk... But I broke my arm," Volkov said at the time. The attack on Volkov came about a month after the death of Navalny. His supporters, his widow Yulia Navalnaya, and many Western leaders have accused Putin of being responsible for his death, but the Russian government has denied the claims. A day before he was attacked, Volkov wrote on social media: "Putin killed Navalny. And many others before that." Hours before the attack, Volkov also told the independent Russian news outlet Meduza that he feared for his safety following the death of the opposition leader. "The main risk now is that we will all be killed. Well, that's pretty obvious," he said. Read Also: Navalny's widow hires security after hammer attack on ally (in Portuguese)