Defence secretary Ben Wallace has ordered an inquiry after revealing that a suspected Russian agent posing as the prime minister of Ukraine had been able to set up a Microsoft Teams call with him through official channels.

Wallace said last week on Twitter that the bid had been a “desperate attempt” that he believed was part of a Russian dirty-tricks campaign, following the invasion of Ukraine.

But the call lasted for several minutes and was only terminated when Wallace became increasingly suspicious that the person posing as Denys Shmyhal was “an impostor”. Home secretary Priti Patel subsequently revealed that she had been targeted in a similar way last week.

Armed Forces minister James Heappey confirmed on Friday that the Ministry of Defence had launched an inquiry into the hoax call, which Wallace suggested had been requested via another government department in the name of an aide at the Ukrainian Embassy.

“Ben’s pretty cross. He’s very cross,” Heappey told BBC Radio 4’s Today programme. “And he’s asked the department to look at how that happened, because it shouldn’t have done.”

The minister insisted that national security would not have been compromised as a result of the call because Wallace had a very clear understanding of subjects that were too sensitive to be discussed on Teams rather than more secure videoconferencing channels.

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“Ben Wallace is a guy that understands threat very well indeed,” Heappey said. “He spent years as security minister before he was promoted into the Ministry of Defence as the secretary of state. He knows when he’s on a top secret [video teleconferencing call], when he’s on a secret VTC and when he’s on a Teams call, and he knows what you can say on each. And, so, knowing that it was on a Teams call, they were exchanging platitudes that you do in those situations.”

Heappey said Wallace’s suspicions had been aroused when he realised the individual posing as Shmyhal would not have asked particular questions relating to military movements via Teams if he really was the Ukrainian prime minister “because the Russians are watching”.

Wallace told the Daily Telegraph that he was in Poland when he took the call from the person posing as Shmyhal yesterday, and that the caller had looked and sounded like the Ukrainian PM – whom the defence secretary said he had never met in person.

He said the call was terminated after eight or nine minutes when questions began to turn to the topic of UK security, including potential deployments of British warships to the Black Sea and the potential for Ukraine to drop its constitution-backed ambitions to join Nato. He told the Telegraph the questioning was becoming increasingly “ridiculous”.

Writing on Twitter, Wallace described the hoax as “an attempt” by an imposter to speak with him. He continued: “No amount of Russian disinformation, distortion and dirty tricks can distract from Russia’s human rights abuses and illegal invasion of Ukraine. A desperate attempt.”

Shortly afterwards, the home secretary detailed a similar experience. 

“This also happened to me earlier this week,” she wrote on Twitter. “Pathetic attempt at such difficult times to divide us. We stand with Ukraine.”

Wallace told the Telegraph he expected clips from his conversation with the hoaxer to be selectively edited and used as propaganda for Russian audiences.

“They'll slice it and dice it and cut out the bits where I say the international community wants Ukraine to be free to choose as a sovereign nation,” he said. “They won't cover my bit about press freedom. They won't cover my thoughts about disparaging president Putin or what [the Russians] are doing in Ukraine is appalling.”

The MoD said it was unable to offer further details about the inquiry at this stage.