Responding to a dressing down from the federal ethics watchdog who said Jim Flaherty broke the rules when he sent a letter to the CRTC advocating for a business in his riding, the finance minister says any wrongdoing was borne of an "oversight."

Ethics Commissioner Mary Dawson’s criticism was made public on the Office of the Conflict of Interest and Ethics Commissioner's website Friday in a notice she also sent him outlining her conclusion after reviewing the case.

In her response, Dawson says Flaherty broke accountability guidelines, as well as conflict of interest rules, when he sent the letter to the Canadian Radio-Television and Telecommunications Commission last March to advocate for Durham Radio Inc. and its ultimately-failed bid for an FM radio station licence.

Nevertheless, Dawson says, considering his political position, Flaherty was wrong to have stepped in on the company’s behalf.

"It is improper for you, as Minister of Finance and Minister responsible for the Greater Toronto Area, to have written a letter of support on behalf of a constituent to an administrative tribunal in relation to its decision making," Dawson wrote.

As news of his letter first made headlines earlier this week, Flaherty told The Canadian Press he would "continue to be a strong advocate for the people and community I represent. It is my job."

The Prime Minister's Office also came to his defence, saying on Thursday that Flaherty was merely performing his duties as an MP.

Flaherty did not only sign his letter as an MP, however, as his sign-off also notes his status as finance minister and minister responsible for the GTA.

"I therefore order you to refrain from writing any similar letters in the future without seeking approval from my office."

In his response Friday, Flaherty said he "fully intended" to send the letter in his capacity as an MP, and not as a cabinet minister.

"It was drafted in my community office and printed on my MP letterhead, and in fact, I insisted the MP reference be added to the text to emphasize the point," he said.

"However, due to an oversight my Ministerial title was used in the signature block. This is regrettable and I can assure the Ethics Commissioner that this will not happen again."

According to the "Accountable Government: A Guide for Ministers and Ministers of State," the decisions of "quasi-judicial tribunals" such as the CRTC must be made free of political interference.

Ministers can return or overturn such agency's decisions once they are made, but the rules state they cannot "intervene, or appear to intervene" in the initial decision-making process.

With files from The Canadian Press