A "huge surge" in applications for postal votes has been recorded in marginal seats after Labour has used new relaxed electoral rules to canvass with postal vote application forms.

A Times survey of 100 constituencies reveals that "the recorded increases already dwarf the Labour majorities" with an average rise in applications of 300 per cent.

The rise in applications for postal votes under the new rules - which have prompted concerns over electoral fraud - are to be investigated by the Electoral Commission.