Tensions between Britain and Iran have heightened following the seizure of UK-flagged tanker Stena Impero A counter-terror operation in 2015 against a Hezbollah-linked found the cell had been stockpiling tons of explosives LONDON: The UK could come under attack from Iranian-backed terror cells if the ongoing Gulf crisis worsens and relations between London and Tehran continue to deteriorate, intelligence sources have said. Senior intelligence officers in the UK now rank the Islamic Republic only behind Russia and China as the severest threat to the national security of the UK, a Daily Telegraph report on Monday said. Tensions between Britain and Iran have heightened following the seizure of UK-flagged tanker Stena Impero in the Strait of Hormuz last week, raising concerns of top intelligence bodies in Britain. According to MI5 and MI6, Iran is funding a network of terror cells across the European continent — including in the UK — and, depending on how the Gulf crisis plays out, could give the green light for attacks to be carried out. A counter-terror operation in 2015 against a Hezbollah-linked cell found the group had been stockpiling tons of explosives on the outskirts of London, something first disclosed by the Telegraph in June, and described as “proper organized terrorism.”A source told the newspaper: “Iran has Hezbollah operatives in position to carry out a terrorist attack in the event of a conflict. That is the nature of the domestic threat Iran poses to the UK.” MI5 and Metropolitan Police said they were confident that the 2015 raids had “severely disrupted” Iranian terror activity in the UK, but that cells still existed on the European mainland. The report also disclosed that Iran had been blamed for a series of cyberattacks on the UK, including hacking of politician’s and peers personal information, on the Post Office as well as local government bodies and private sector companies in 2018. The UK government has sent a letter of protest to the UN Security Council over the seizure of the tankers in “Omani waters when it was interrupted by Iranian forces,” which it says is an “illegal interference by Iran.” The UK government has consistently said it does not seek confrontation with Iran, but the letter added: “It is unacceptable and highly escalatory to threaten shipping going about its legitimate business through internationally recognized transit corridors.”