Douglas Alexander, the minister criticised over the Scottish election fiasco, last night demanded an apology from those politicians who had "impugned his integrity".

After the publication of a critical report into the voting shambles earlier this week the former Scotland Secretary, who is now at the International Development Department and Gordon Brown's General Election co-ordinator, was accused by MPs of "having his finger in the till" and of "attempted gerrymandering".

But yesterday Ron Gould, the Canadian election expert who wrote the report, said in a letter to the Electorial Commission that he had never suggested specific actions were taken by ministers to advance their own party's interests.

In the light of Mr Gould's comments Mr Alexander now wants an apology from politicians including Tory leader David Cameron, shadow Scotland Secretary David Mundell, First Minister Alex Salmond and Scottish LibDem MP Alistair Carmichael.

A spokesman for Mr Alexander said: "To impugn his integrity was always wrong, and now Ron Gould has confirmed as much."

Mr Mundell, responding to the Gould letter, said: "The blame has already been accepted by Douglas Alexander."

In his letter, Mr Gould said all political parties were to blame for May's election problems. The letter, he explained, was intended to "clarify" his report's findings after argument among political parties over who was the main target of his criticism.

In his clarification he set out how he reached his findings.

"I did not suggest in the report specific actions were taken by ministers to advance their own party's interests but that all political parties were concerned with the potential political advantage that could be gained by certain decisions, such as on the question of ballot paper design, and this delayed key decisions."

He concluded that "while responsibility for taking these decisions lay with the Scotland Office and the Scottish Executive, all political parties were involved in the long-running debates, contributed to the final decisions and shared in the failure to prioritise the interests of the voter."

Meanwhile, a senior Labour figure acknowledged "administrative" responsibility for the Holyrood elections could be transferred to Scotland. Former minister Andy Kerr said he would be relaxed about the move.