The WC-135 Constant Phoenix, which is specially modified to collect atmospheric samples, flew out of RAF Mildenhall on a mission to find evidence of nuclear activity or explosion, according to strong rumours.

Specialist equipment enables the crew to detect radioactive debris ‘clouds’ in real time - after such a cloud was believed to be heading towards northern Europe and the Barents Sea.

News of the deployment comes amid claims Russia may be testing nuclear weapons, either to the east or in the Arctic, after a spike in radioactivity was reported.

The WC-135 Constant Phoenix, which is known as a nuclear ‘sniffer’ plane, was deployed to Britain last week on an undisclosed mission.

Air quality stations in Norway, Finland, Poland, Czech Republic, Germany, France and Spain have detected the presence of Iodine-131 at low levels. This has fuelled speculation that the WC-135 has been called in to investigate the cause of the higher-than-normal levels of Iodine-131.

The spike has sparked speculation that Russian president Vladimir Putin is testing nuclear weapons in Novaya Zemlya near the Arctic. However, the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organisation) ruled out a nuclear test had recently taken place.

Similar aircraft were used in the wake of the Chernobyl nuclear plant disaster in the Soviet Union in 1986 and the Fukushima incident in Japan six years ago by collecting particles and chemical substances in the atmosphere, days, weeks and months after they were dispersed. The deployment of the WC-135 aircraft, which detects and identifies explosions from the air and was used after the Chernobyl disaster in the Soviet Ukraine in 1986, adds weight to the argument.

An air filter station in Svanhovd, Norway, was the first place to measure the Iodine-131 in the second week of January. Next it was measured in Rovaniemi, in Finnish Lapland. Within two weeks, it was traced in Poland, Czech Republic, Germany, France and Spain.

This movement led the Norwegian Radiation Protection Authority (NRPA) to suggest the particles may have originated in Eastern Europe. It’s possible that the particles could have come from an incident at a nuclear reactor.