Russia has demanded an explanation from British authorities over their search of an Aeroflot plane at London's Heathrow Airport, saying British airlines could face similar actions if London does not clarify what happened.
The Russian Foreign Ministry said British customs authorities boarded and searched the plane after it arrived from Moscow and passengers disembarked on March 30, without providing any explanation of their reasons for the search.
Ministry spokeswoman Maria Zakharova called the incident a “provocation,” coming amid severe strains between the two countries.
The Russian Embassy in London said the "extraordinary" search was conducted by British Border Force and customs officials.
The embassy said it sent a diplomatic note demanding that Britain provide an explanation for the incident.
London's Metropolitan Police denied that they were involved in any search of an Aeroflot flight.
But British Security Minister Ben Wallace said in a March 31 statement that it was "routine for Border Force to search aircraft to protect the U.K. from organized crime and from those who attempt to bring harmful substances like drugs or firearms into the country."
The Russian Transportation Ministry, meanwhile, said in a March 31 statement that it would seek an official explanation from Britain and would deem the search illegal if it did not receive an answer.
The ministry said it would also reserve the right to conduct similar actions against British airlines if it does not receive a response.
Russia's latest accusation against Britain came on the same day Russia served expulsion notices to dozens of staff from Western embassies in a diplomatic tit-for-tat ignited by the poisoning of former Russian spy Sergei Skripal and his daughter, Yulia.
The Skripals were found slumped on a bench in the southern English city of Salisbury on March 4. Britain says they were poisoned with a nerve agent and that Russia is responsible.
Moscow has denied it was behind the attack and has called on Britain to prove it did not itself poison Skripal, 66, and his 33-year-old daughter.