Defence Secretary Ben Wallace has strongly rejected Russian claims that Western powers are colluding with Ukraine on a “provocation” involving a radioactive “dirty bomb”

Russian defence minister Sergei Shoigu made the allegation in a series of telephone calls with counterparts from the UK, the United States, France and Turkey.

According to the Russian defence ministry, he voiced concern about “possible Ukrainian provocations involving a ‘dirty bomb’” – an explosive device which spreads radioactive contamination.

Mr Wallace rejected the charge and warned Moscow not to try to use it as a “pretext” for its own efforts to step up the conflict.

In a statement, the Ministry of Defence said: “Minister Shoigu alleged that Ukraine was planning actions facilitated by Western countries, including the UK, to escalate the conflict in Ukraine.

“The Defence Secretary refuted these claims and cautioned that such allegations should not be used as a pretext for greater escalation.”

The Russian authorities have repeatedly made allegations that Ukraine could detonate a dirty bomb in a “false flag” attack and blame it on Moscow.

The Ukrainian authorities, in turn, have accused the Kremlin of planning such an attack.

Ukraine’s presidential adviser Mykhailo Podolyak dismissed Mr Shoigu’s claims as an “absolute and quite predictable absurdity from those who believe that they blatantly lie and make people believe in that”.