Isis released a propaganda video showing the beheading of a man named as Evgeny Petrenko, a Russian intelligence officer
The lengthy video repeated the format used in previous hostage executions, including of James Foley and David Haines, showing a prisoner identified as Evgeny Petrenko giving a “confession” under duress.
He was shown dressed in a black jump suit speaking with militants in prison, before kneeling in a desert and urging other Russian agents to surrender.
“This idiot believed the promises of his state not to abandon him if he was captured,” Mr Petrenko said, before he was beheaded by a Russian-speaking Isis militant.
He was shown supposedly confessing to attempting to infiltrate jihadi groups in the Caucus, Turkey and Syria, where he allegedly contacted Chechen militant Omar al-Shishani, who has since been killed in a US air strike.
The footage, released by Isis’ al-Furat propaganda wing, included clips of several other Russian prisoners being beheaded and shot in past videos.
It also included footage of Russian air strikes in Syria and alleged civilian casualties, as well as of a Russian helicopter going down and protests against Vladimir Putin.
Isis named Mr Petrenko as a Federal Security Service (FSB) colonel in a previous propaganda video released in September, threatening to execute the prisoner in a “message to the President of Russia and its people”.
The execution footage was released on Isis propaganda channels on Tuesday, as huge military parade rolled through Moscow to mark the anniversary of its victory over Nazi Germany in 1945.
Mr Putin’s forces are bombing Isis and aiding Syrian forces on the ground as part of an intervention in support of Bashar al-Assad, recently regaining territory in Palmyra and Homs province.
Previous high-profile executions have sparked retaliation by affected countries, with a spate of Isis beheadings in 2014 driving public will for intervention by the US and Britain.
Dozens of countries are now part of the international coalition supporting Operation Inherent Resolve, which has carried out thousands of air strikes on Isis strongholds in Iraq and Syria.
The terrorist group has lost swathes of the territory it seized in a lightning advance in 2014, with jihadis being driven out of Mosul and surrounded in their de-facto capital of Raqqa.
Analysts have warned that the group is increasingly turning to international terror attacks as a way of retaining legitimacy and momentum in the face of military defeat on the ground.Isis’ propaganda magazines have released detailed instructions on carrying out massacres using lorries, cars, knives, guns and bombs, which have been tied to recent attacks in London, Stockholm and Paris.