Universities and Labour councils have been accused of registering thousands of students to vote without their knowledge in a bid to boost labours chances of winning the December 12 general election.
An investigation in uni city Plymouth has so far identified 850 students and under 17-year-olds on the electoral register who had not completed their own applications.
Of those, 352 had already received polling cards from the Labour council before sceptics blew the whistle.
It is illegal to register anyone else to vote.
Three Tory candidates in the South West last night wrote to the Electoral Commission to ask for a full investigation amid suspicions the same process is being carried out nationwide.
One candidate, Defence Minister Johnny Mercer, told The Sun: “My fear is many councils and universities might also be doing this.
“Where seats are held or lost with just double digit numbers, this practice could have a strategic impact in the outcome of elections.”
The illicit Plymouth registrations affect three constituencies.
Two — Plymouth Moor View and Plymouth Sutton and Devonport — are expected to see close fights between Tories and Labour.
Students and the under 24s predominantly back leftwing parties and favour Remain over Leave.
Last night Plymouth Council admitted a “procedural error” meant student information was uploaded to its electoral system before the students had a chance to register.