The Uefa president, who is standing for the Fifa presidency, sent a letter to all 54 member associations insisting the payment was above board but admitted the controversy could harm his image.
Outgoing Fifa president Sepp Blatter has also stated he will remain in the post despite the opening of criminal proceedings against him because he “has done nothing wrong or improper”, according to a statement from his lawyer.
The timing of the payment to Platini in February 2011 raises questions: It came just after the Frenchman had met Asian football chief Mohamed Bin Hammam, who urged him to stand against Blatter, and two months before Uefa gave its backing to Blatter.
Scottish FA chief executive Stewart Regan said the issue of the nine-year gap needed to be explained while the FA is also keeping a close watch on developments and is expected to discuss the situation at a board meeting on Wednesday.
Regan said in a reply to a question about whether he would ask about the nine-year gap: “Absolutely... it is an essential piece of information that still needs to be provided.”
The proceedings against Blatter were opened by the Swiss attorney general on Friday and concerned TV rights deals sold to the former Fifa vice-president Jack Warner and the payment to Platini. Both Blatter and Platini are now being investigated by Fifa’s ethics committee.
Platini said in his letter: “You will surely understand that firstly I have not been accused of any wrongdoing, and secondly that as a matter of respect, I will refrain from making detailed statements in connection with the ongoing investigation.
“Still, for reasons of transparency, I would like to inform you about the following important aspects.
“I wish to clarify that for the period 1998 to 2002 I was employed by Fifa to work on a wide range of matters relating to football. It was a full-time job and my functions were known by all. The remuneration was agreed at the time and after initially payments were made, the final outstanding amount of 2m Swiss Francs was paid in February 2011.
“This income has all been fully declared by me to the authorities, in accordance with Swiss law.
“I was interviewed by the Swiss authorities about this matter last Friday, not as a person accused of any wrongdoing, but simply in my capacity as a person providing information.
“Furthermore, I have, today, written to the ethics committee of Fifa to request that I may come forward and provide whatever additional information may be needed in order to clear this matter up.
“I am aware that these events may harm my image and my reputation and by consequence the image of Uefa, the organisation of which I am proud to be president. For these reasons, I wish to use all my energies to ensure that any issues or misunderstandings can be resolved as soon as possible.”
Blatter also insisted the payment to Platini was legitimate but did not explain the delay.
A statement from Blatter’s lawyer said: “President Blatter spoke to Fifa staff today and informed the staff that he was cooperating with the authorities, reiterated that he had done nothing illegal or improper and stated that he would remain as president of Fifa.”
The statement added: “On the Platini matter, President Blatter on Friday shared with the Swiss authorities the fact that Mr Platini had a valuable employment relationship with Fifa serving as an advisor to the president beginning in 1998.
He explained to the prosecutors that the payments were valid compensation and nothing more and were properly accounted for within Fifa including the withholding of social security contributions.