Moving English tests online for migrants who want a visa to come to the UK could open the door to fraudsters and criminal gangs, the largest international providers of English language exams have warned. Under the new £816m contract, which could be operational by December, English exams for Home Office visas would become "fully digital" and could be sat at a location of an applicant's choosing. In a letter to the Home Office, the largest consortium of current providers warned Home Secretary Shabana Mahmood the move risked undermining her wider goals to secure UK borders. The letter, seen by the BBC, said there was a danger applicants would be able to fake test results with the help of imposters and AI. The Home Office said it would not comment in detail on a live tender and was still in the process of finding a provider who would meet the highest thresholds of data security and fraud prevention.…