The British government was in turmoil on Friday as a major investigation was launched into leading cabinet members over who leaked a controversial decision not to ban a Chinese firm from future telecommunications networks. It comes after details emerged from the confidential meeting of the UK’s National Security Council on Tuesday that Chinese telecoms firm Huawei could be green lighted for a limited role in developing its 5G network. The senior minsters, including heavily tipped frontrunners to replace Prime Minister Theresa May, were given a strict deadline to comply with an investigation into the scandal which will likely involve their personal phones being seized and email accounts being checked. Cabinet secretary, Sir Mark Sedwill, the UK’s most senior civil servant, wrote to all the ministers who attended the meeting requesting their consent by the strict deadline and asked them to confess or deny whether they were involved in the leak. The controversial decision has sent shockwaves through the government over security concerns surrounding the company’s links with the Chinese government. Under Chinese law, firms must support the state’s intelligence work. Large enterprises are also embedded with Communist Party cells that promote state interests. It is understood the politicians present had been deadlocked at five a piece and the Prime Minister was forced to cast the deciding vote in favour of the firm. The first ministers to deny the leak were the Uk’s Foreign Secretary Jeremy Hunt, who described it as “utterly appalling”, and Defence Secretary Gavin Williamson, who called it "completely unacceptable". National Security Council discussions are only attended by senior ministers and security officials who first sign the Official Secrets Act that commits them to keep all conversations private or risk prosecution. However, shortly after the meeting concluded a British newspaper broke the news. Former cabinet secretary Gus O'Donnell told BBC radio that the disclosure of National Security Council information was "incredibly serious" and a "complete outrage". "This is really important for the country, these issues are massively important," he said. On Friday, Britain’s finance minister Philip Hammond said: "My understanding from London (is) that an investigation has been announced into apparent leaks from the meeting earlier this week. "To my knowledge there has never been a leak from a National Security Council meeting before and therefore I think it is very important that we get to the bottom of what happened here. "It’s not about the substance of what was apparently leaked. It's not earth-shattering information. But it is important that we protect the principle that nothing that goes on in national security council meetings must ever be repeated outside the room." The United States, which is adamantly opposed to Huawei's involvement over fears its equipment could be used for espionage, has said it will be looking closely at the UK decision. Rob Joyce, a senior adviser at the US National Security Agency, told the Financial Times it did not want to hand Beijing a “loaded gun”. “We have got to understand all the details of that and decide what that means,” he said. “What we will be insistent on is UK decisions can’t put our information at risk but the good news is that the UK already understands that.” Mrs May's spokesman declined to comment on the leak but said a formal decision on Huawei would be made by June. “The prime minister is clear that the protection of information on matters of national security is of the highest importance,” he added. The scandal follows months of turmoil in the UK over its stalled Brexit talks which have resulted in several ministers resigning. Mrs May has promised to step down as soon as she gets the first stage of Brexit finalised, the extended deadline for the process is now October 31. Her commitment to quit has only fomented cabinet rivalries as various ministers jockey for position in a looming leadership race.