"We thought Johnson could be more expressive," Stolyarov told Sputnik speaking on behalf of himself and his fellow prankster Vladimir Kuznetsov.
Also known as Lexus, Stolyarov explained why the pair chose to pose as the new Armenian leader Nikol Pashinyan.
"We tried to call him [Johnson] before, as authorities of Ukraine, but he didn't want to talk to them. So PM of Armenia is unknown now, he is new — that's why we decided to call as PM Pashinyan. We read an article where the Minister of State for Europe and the Americans Sir Alan Duncan congratulated Pashinyan. We first called him and had a conversation with him and then he organized the conversation with Boris Johnson."
The fake Pashinyan quizzed Johnson on how 'he' should deal with the Russian President Vladimir Putin and asked the FM about the Sergei Skripal poisoning case.
Asked whether he was sure it was Mr. Putin who tried to kill ex-spy Sergei Skripal in Salisbury, Mr. Johnson said:
"We're pretty sure — we're, like, almost 100 percent sure. We will be able to do more to illustrate that."
"It was interesting that he said the OPCW confirmed that Novichok was produced in Russia but as we know that the head of that organization told us in our conversation that it is not true," Stolyarov told Sputnik.
READ MORE: 'Citizens With Strong Position': Prankster Calls OPCW Head Amid Skripal Case
One of the pranksters asked how Pashinyan should behave during his meeting with Putin in Sochi, to which Johnson replied:
"I think it is very important, Prime Minister, that we don't have a new cold war. I don't want that. Nobody in the UK wants that. If I have a message to Putin, it's that we don't want a cold war but we do want to see an improvement in the way Russia behaves."
Britain's top diplomat also added that the "only thing the Russians respond to is determination and firmness."
Stolyarov told Sputnik he found it interesting that in a private conversation Mr. Johnson didn't ask "Pashinyan" to resist Russia.
In the audio clip, Mr. Johnson says Britain will continue to tighten the squeeze on some of the oligarchs who surround Putin.
"You throw a stone in Kensington and you'll get an oligarch," he told the pranksters.
READ MORE: 'A Security Risk': Public Demands Johnson's Resignation Over Nerve Agent Gaffe
The FULL 18 MINUTES!!! 😂😂😂#BoJoFCO https://t.co/qUUeTvxXfj
— Nic Boothby (@NicBoothby) May 24, 2018
When a prankster can pretend to be a President & talk to @BorisJohnson for 18 minutes you have to question how that just happened. https://t.co/2VQWnJfSJY
— Hugh Frazzles (@HughFrazzles) May 24, 2018
Boris Johnson tho! 🙈 #Boris pic.twitter.com/dfAhXG5umD
— Danny Partington (@DannyPart) May 24, 2018
Following the hoax, UK's Foreign Office issued a statement, saying that "the Foreign Secretary realized it was a hoax, and ended the call."
"We checked it out and knew immediately it was a prank call. The use of chemical weapons in Salisbury and Syria, and recent events in Armenia are serious matters. These childish actions show the lack of seriousness of the caller and those behind him," the statement said.
Boris Johnson tricked by Armenian pranksters. Bit rich him calling it childish!!!!
— Peter Millar (@peterjmillar) May 24, 2018
READ MORE: The 'Best' of Boris: UK Top Diplomat & the Art of Being Ill-Equipped