BREAKING: Russia threatens to storm ALL UK planes in retaliation for Heathrow incident

They allegedly boarded the flight "without grounds" shortly after it touched down at 3.37pm. Police then "insistently" asked passengers and crew to leave but the pilots refused, according to multiple reports in Russia. Moscow will deem the search illegal and taken similar action against British airlines unless the episode is clarified, its Transport Ministry confirmed. 

Brits heading to the World Cup in June may now be affected by random searches. Arsenal fans will also jet off to watch the Gunners play CSKA Moscow on April 12. The Russian embassy in Britain complained about the search at the time. Maria Zakharova, a spokeswoman for the Russian Foreign Ministry, said: “The British authorities asked the Russian crew, including the captain, to leave the plane.

"The commander of the aircraft proposed the inspection to be conducted in his presence as he’s forbidden from leaving the plane in accordance with the regulations. "At the moment, the police proceed with the search without releasing the commander from the cabin and preventing him from being present during the inspection." 

The Kremlin has called the incident "another provocation" amid simmering tensions over the nerve agent attack on a former Russian spy. Sergei Skripal, 66, and his daughter Yulia, 33, were exposed to nerve agent Novichok earlier this month in Salisbury. Yulia is now “conscious and talking” after making a miracle recovery but her dad remains in a critical condition. Prime Minister Theresa May said Russian President Vladimir Putin was “highly likely” behind the attack, but the Kremlin has repeatedly denied any involvement.