It is understood the committee concluded via a majority that the First Minister misled them about a meeting she held with the former first minister in her home on April 2, 2018.
Specifically, it is reported that Ms Sturgeon did offer to intervene in the harassment complaints process, something she repeatedly denied in both her written and oral evidence.
The Scottish Government’s ministerial code states that a minister who “knowingly” misleads the Scottish Parliament is expected to offer their resignation.
Pressure on the First Minister to resign following the finding will likely now intensify ahead of the publication of the concurrent investigation by the independent adviser on the ministerial code, James Hamilton QC.
That investigation is considered by insiders to be key to Ms Sturgeon’s future and, if it also finds she breached the ministerial code, more likely to force a resignation.
The committee’s decision, which leaked last night, was reached via majority, with five votes including the four opposition committee members and independent MSP Andy Wightman against the four SNP members.
A spokesperson for the First Minister said last night: “The First Minister told the truth to the committee in eight hours of evidence, and stands by that evidence.
“It is clear from past public statements that opposition members of this committee had prejudged the First Minister at the outset of the inquiry and before hearing a word of her evidence, so this partisan and selective briefing – before the committee has actually published its final report – is hardly surprising.
“The question of the First Minister’s adherence to the ministerial code is being considered independently by James Hamilton, and we expect to receive and publish his report soon.”
Sky News first reported that the committee believe that Ms Sturgeon did offer to intervene, an allegation brought by Mr Salmond and corroborated by his legal adviser.
The committee concluded that she provided an “inaccurate account” to the committee and by doing so misled the Scottish Parliament.
The leak from the committee comes ahead of the conclusion of the report writing process ahead of its publication.
In response to the reports of the committee’s conclusion, Holyrood officials said the report will be published in full on Tuesday at 8am.
The separate Hamilton report is expected to be published within the next week.
Mr Salmond had argued during his evidence session in front of MSPs that the First Minister had offered to intervene.
He told the committee: “She said she would when it was the appropriate time. As I say, the conversation was not about if she would intervene, but when.”
The former first minister’s lawyer, Duncan Hamilton, corroborated this account during his written evidence, telling MSPs he heard Sturgeon offering to intervene during the meeting between the two SNP figures on April 2.
He said: “I can confirm that the First Minister did offer to assist. We discussed mediation. My clear recollection is that her words were ‘If it comes to it, I will intervene.’”
In Ms Sturgeon’s written evidence she states that she “made clear” to Mr Salmond that she “would not seek to intervene in it”, and repeated the claim during her eight-hour session in front of the committee.
However the committee believes this to be a fundamental contradiction of other evidence, concluding it is a “potential” breach of the ministerial code.
The committee is examining botched handling of harassment complaints against Mr Salmond by the Scottish Government which led to a £500,000 legal bill after the former first minister succeeded in challenging the process during a judicial review.
Mr Salmond was also acquitted of sexual offence charges in a trial last year.
New Scottish Labour leader Anas Sarwar said last night he would not pre-judge the committee's report before it was published.
He said: “I am not going to prejudge the outcome of the committee report and we await its findings, but if it does conclude that the First Minister has misled Parliament and potentially breached the ministerial code then that is incredibly serious.
“This is about the integrity of our Scottish Parliament and upholding standards in public life.
“The separate Hamilton inquiry has yet to report, and all parties must be given due process, however the code which the First Minister has promised to follow by the letter is clear - any minister who is found in breach of the ministerial code has a duty to resign.”
Scottish Conservative leader Douglas Ross said: "The Committee will publish its findings in the coming days and we will wait for that report. However, we are really only waiting for confirmation of what we already know.
"We have detailed that the First Minister misled the Scottish Parliament.
"Nicola Sturgeon has not told the public the truth about what she knew and when.
"We cannot set a precedent that a First Minister of Scotland can mislead the Scottish Parliament and get away with it.
"We have to trust that the First Minister will be truthful. We no longer can.
"It is the duty of Scotland's opposition to hold the government to account. That is what the Scottish Conservatives have done throughout this sorry affair, which has so badly let down the women who came forward and damaged the standing of Scotland's institutions.
"We have called out the First Minister based on the overwhelming evidence that she misled Parliament. We will continue to hold her to the same standards as previous First Ministers of Scotland and demand that she resigns."
The reports came as the Prime Minister refused to comment on whether the First Minister must go if she’s found to have broken the rules, despite Mr Ross calling for her to do so.
Asked at the Downing Street press briefing, he said: “I think your question was an attempt to get me to comment on something which I think is properly and rightfully left to the parliament in Scotland to address, and the Scottish electorate.”
A Scottish Parliament spokesperson said: “Further to media reports on the Committee’s findings, the Committee is still finalising its report.
"There will be no further comment on the report ahead of its publication.”