Andrei Kelin warned his counterpart that the country is “too deep” into the conflict and said he has evidence that British forces were involved in a Ukrainian assault on Russia's position in the Black Sea.
On Thursday, Mr Kelin was asked if Moscow could use a tactical nuclear weapon in the war.
He replied: "No. The world has every assurance that Russia is not going to use [a] tactical nuclear weapon in [the] Ukrainian conflict."
Mr Kelin said he had handed evidence of British involvement in the Crimean Black Sea to his opposite number and added that "it will become public pretty soon”.
He said: “We perfectly know about [the] participation of British specialists in [the] training, preparation and execution of violence against the Russian infrastructure and the Russian fleet in the Black Sea. We know that it has been done."
He added: "And this is a warning actually that Britain is too deep in this conflict. It means the situation is becoming more and more dangerous."
His interview with Sky came after the United Nations’ [UN] nuclear agency said its inspections in Ukraine found no evidence of radioactive "dirty bomb" activity alleged by Russia.
The International Atomic Energy Agency said on Thursday that the inspections requested by the Ukrainian government "did not find any indications of undeclared nuclear activities and materials".
The agency said its experts carried out inspections in three locations in Ukraine and were given unfettered access to the sites.
"Based on the evaluation of the results available to date and the information provided by Ukraine, the agency did not find any indications of undeclared nuclear activities and materials at the locations," it said in a statement.
Top Russian officials, including president Vladimir Putin, have made repeated claims that Ukraine planned to detonate a bomb that scatters radioactive waste in a false flag operation it would try to pin on Moscow.