“(This was) aimed at slandering one of us,” Mr Putin said without humour.

“This is about our interaction which is an important factor for domestic politics. To be honest with you, we did not suspect that this (criticism) could be made with such arrogance with such rudeness, and you know, so unethically.”

Though he insisted it was not a threat, Mr Putin reinforced a warning from Mr Medvedev on Tuesday that the West should be sure to treat Russia as an equal partner when it came to designing and operating a new missile defence shield.