Conservative Tony Baldry has apologised to the Commons over breaches of the MPs' code of conduct.
Mr Baldry gave a "heartfelt and unconditional apology".
It follows a probe by the standards and privileges committee into the way he recorded business interests in Sierra Leone, and use of Commons notepaper.
Mr Baldry, International development committee chair in the last Parliament, "breached" the code in several ways.
One instance was a letter to a minister about a company in which Mr Baldry had an indirect financial interest.
On January 14 2005, he wrote to International Development Secretary Hilary Benn asking if his department could meet with the representatives of a company called Milestone.
In the letter Mr Baldry acknowledged that he had been asked to become its chairman, but what he failed to mention was his financial interest in another company, Red Eagle Resources plc.
In November Mr Baldry had signed a joint participation agreement on behalf of Red Eagle with Milestone in which the two companies pledged to work together in promoting their businesses in Sierra Leone.
The next month Red Eagle billed Milestone for £22,060 in professional charges.
And under the terms of the joint agreement, Red Eagle stood to obtain a 3% shareholding in Milestone if it floated successfully on the stock market - possibly worth about £1.5m.
Breached 'advocacy rule'
Mr Benn replied to Mr Baldry's letter that his department could not endorse individual companies or carry out requested checks.
The committee concluded: "We agree with the commissioner (parliamentary commissioner on standards and privileges committee, Philip Mawer) that Mr Baldry should have declared his existing financial interest in Milestone through the partnership agreement and that, as a result, the secretary of state was not aware of the full scope of his financial links with Milestone.
"While we share the commissioner's view that this omission is unlikely to have influenced the nature of the secretary of state's response, given its terms, we agree with the commissioner that Mr Baldry did not fully comply with the House's requirements in respect of the declaration of interests in his correspondence with the secretary of state."
Mr Baldry was also found to have breached the "advocacy rule" which bans MPs from approaching ministers if the purpose is to confer a benefit exclusively on a body or individual outside Parliament from which the MP has received, is receiving, or expects to receive a financial benefit.
The commissioner and the committee agreed that there was no indication that Mr Baldry sought to exploit his position as chairman of the International Development Committee to further his private interests.
In the Commons Mr Baldry said he had apologised to Mr Benn for anything he had got wrong in his letter.
"My letter to the secretary of state was clearly very poorly written as it has led to a number of misunderstandings but I have to accept, because I wrote the letter, the consequence of those misunderstandings fall to me."
"I do not believe that there was anything in the commissioner's findings or the committee's report that suggests I have done anything ignoble, dishonest or discreditable.
"I hope that the House will accept this as a heartfelt and unconditional apology for what I got wrong and I hope that any fair-minded person reading the commissioner's report will conclude that what I got wrong was by way of inadvertence and omission rather than any deliberate attempt in any way to abuse my position as a member of this House."