Tucker Carlson told Chris Cuomo that he 'can't even guess' who killed Alexei Navalny during a confrontational exchange in which Cuomo hit at Carlson for asking Vladimir Putin softball questions. 

Cuomo will air the two-part chat with Carlson - often rivals during the Trump era when they hosted competing cable news shows - Monday and Tuesday night on NewsNation.

While conceding that Carlson shouldn't have been 'getting into a shouting match' with the Russian president, Cuomo still felt the ex-Fox News host could've gone harder and asked about Navalny.

'[You] made choices,' he said. 'You didn't ask about Navalny. You said, well all killers, all leaders kill. But don't you feel that if you are gonna go and sit with someone like that you have to hold them for account for things that matter, the fact that he may have murdered somebody or a lot of people.'

Carlson responded by saying that he did hold Putin to account but claimed that 'Ukrainians say [Putin] didn't kill Navalny.'

Cuomo responded: 'Who killed him then? Guy looks good one minute, the next minute he's dead.'

'In some larger sense, the Russian government, the Ukrainian government said he died of natural causes,' Carlson argued. 

'Now, what is actually going on there, I can't even guess.' 

Ukraine's top spy chief has claimed that Navalny may have 'died from a blood clot' amid widespread speculation that the outspoken Putin critic was murdered by Russian spies.