Birmingham City Council chief executive Lin Homer dismissed claims she was not interested in defeating postal vote fraud, and insisted she was doing everything possible within the law to tackle corruption.
Mrs Homer has taken the unprecedented step of writing to 50,000 people in Birmingham's 11 parliamentary constituencies asking them to confirm that their request to vote by post at the General Election is genuine.
The move comes after an elections court in Birmingham heard allegations of widespread postal vote fraud at the 2004 city council elections. Thousands of voting forms were deliberately misdirected to "safe houses" where they were illegally filled in to favour Labour candidates, it is claimed.
Deputy council leader John Hemming criticised Mrs Homer, who is the returning officer, for refusing to hand over a list of all people registered to vote by post.
Mrs Homer said she was prevented by the Data Protection Act from doing so.
She said advice received in December from the Electoral Commission made it clear the council could not distribute lists to prospective parliamentary candidates until after the dissolution of Parliament.
Writing to people on the postal vote register was a far more effective way of protecting the "integrity of the vote", she insisted.
She would be abrogating her own responsibility if she allowed political parties to control the process for checking the authenticity of postal vote requests.
"Given the action I am already taking to verify the list of postal voters in advance of a future election, I feel that any legitimate concerns raised by Councillor Hemming are amply met," she said.
Mrs Homer added: " Although it is rumoured that a General Election will be held on May 5 a person is not allowed to have the list of postal voters until the dissolution of Parliament at the earliest.
"Councillor Hemming is entitled to look at certain records at the elections office relating to the matters he has said he is concerned with. However, the elections officer is bound by the Data Protection Act 1998."
Mrs Homer added: "I share the concerns about postal voting and that is why I have written to these people.
"It is a much more robust way than relying on political parties somehow to do the checking process. That is me taking my responsibilities very seriously."
Mrs Homer appealed to everyone who received a letter to reply.
The Government should consult urgently on changes to the way the electoral roll is compiled, to counter a slump in registrations and growing fears of fraud, MPs said today.
As postal voting becomes more common, there is a "strong case" to tighten protection against fraud by requiring voters to register themselves individually, rather than collectively as a household, they said.
But they acknowledged that experience in Northern Ireland, where 144,000 voters disappeared from the roll after individual registration was introduced in 2002, made it essential to make any changes in the rest of the UK with caution.
Today's report also voiced support for the creation of a national electoral roll, based on locally-maintained registers, and expressed " particular concern" over delays in the development on the Co-Ordinated Online Register of Electors (CORE), which has already slipped back by a year since its launch in 2004.
The Office of Deputy Prime Minister John Prescott last year indicated he was ready to look at the introduction of individual registration, which is strongly supported by the Electoral Commission.