The letter emerged yesterday as Labour continued to demand an independent inquiry into the scandal that brought down Dr Smith.
ACC chairman John Judge yesterday confirmed it was Ms Pullar's approach to another old friend, ACC board member John McLiskie, last year which led to a controversial meeting with senior corporation managers in December.
Ms Pullar yesterday issued an apology to Dr Smith, who she said was "only trying to help a mate" but she also detailed her own privacy grievance against the corporation.
A senior minister in John Key's Government, Dr Smith resigned his portfolios this week after the Herald revealed he had interfered in ACC's handling of his long-time friend and National Party activist Ms Pullar's claim while he was ACC Minister last year.
Revelations about two inappropriate letters he wrote in support of Ms Pullar's claim emerged amid an ongoing scandal over a huge breach of privacy by the corporation which in August last year accidently sent Ms Pullar a file containing the personal details of 6700 other ACC claimants.
In the December meeting Ms Pullar allegedly tried to extract benefits in exchange for returning that information.
Labour's ACC spokesman, Andrew Little, said it was known a board member was involved in setting up that meeting.
"There's a question about what he knew at what time and his role in the December meeting."
Mr Judge confirmed Mr McLiskie was the ACC board member who Ms Pullar approached with her claim some time after she received the information.
The Nelson-based Mr McLiskie, like Ms Pullar, is a former employee of apple marketing firm Enza.
"He knew her," Mr Judge said.
However, it was not unusual for board members to be approached by friends and acquaintances about their claims and there were strict rules about such approaches.
"She spoke to John, he quite properly asked for it to be put in writing which was done. It was passed to me, I passed it to a senior staff member and asked them to review it and give me the appropriate assurances."
The ACC yesterday confirmed that ACC's Philip Murch, who met Ms Pullar, would have seen the letters Dr Smith wrote in support of her but Mr Judge said that would not have influenced his treatment of her.
"I absolutely don't believe it would have made any difference whatsoever."
Meanwhile, the Prime Minister was yesterday resisting calls for an independent inquiry. "Everyone has moved on. There is nothing I have seen in the paperwork I have that gives me concern about the need for an investigation."
However, Dr Smith himself has said he would like an independent investigation in order to clear himself of any other improper action while ACC minister.