Sam Younger, the chairman of the Electoral Commission, has written to Nick Raynsford, the local government minister, urging the Government not to exploit a loophole in the law ahead of this autumn's referendums in the North-East, North-West, and Yorkshire and Humberside.
Under the anomaly, the Government can run information campaigns with an unlimited budget until four weeks before a referendum. But strict spending limits for other groups, including the Yes and No camps, apply ten weeks before the vote.
Younger said: "What makes sense in fairness is that the Government should operate under the same restrictions as everybody else. In a ten-week referendum period, you have got something that is undesirable - a period of six weeks in which those participating are under limits of what they can spend, and for that period the Government isn't."
He asked the Government to build into its planning that it would not run ads during the six-week period in question. But Raynsford has refused to give such a pledge, saying that time may not permit such a gap.