Business Secretary John Hutton said firms will also have to publish detailed decommissioning plans before construction of a new site starts.
Mr Hutton said it was in the national interest to make sure taxpayers were protected from clean up costs of nuclear power.
He said: "Let me be clear - full means full. Funds will be sufficient, secure and independent, it will be a criminal offence not to comply with the approved arrangements and we are taking powers to guard against unforeseen shortfalls."
Energy companies have been asked to submit plans to build new nuclear power stations, and it is estimated that a decision to start building could be made in mid-2009.