Orange confirmed it was helping the authorities with an investigation into IT expert Anthony Benfield, who has also carried out work for other British companies, including private health group Bupa.
Mr Benfield is reported to be part of a wider investigation by British security services into the passing of secret computer files belonging to British companies to the French intelligence service.
An Orange spokeswoman told BBC News Online that the company was not aware of any breaches in security while Mr Benfield was working with its IT department.
French take-over
The telecoms company only learned of an investigation into Mr Benfield's alleged activities after he had left, she said.
Earlier this year France Telecom paid £31bn for Orange, which was then owned by Vodafone.
The takeover deal followed a competitive auction against rival European and American telecoms companies.
Any inside information about Orange could have given France Telecom increased confidence during the negotiations.
A spokeswoman for Orange said Mr Benfield had stopped working for the company in September 1999, when his 18 month contract came to an end.
"There is no evidence that he had access to any sensitive information", she said.
Mr Benfield left Orange before France Telecom expressed an interest in buying it, she added.
Bupa
Bupa also confirmed that Mr Benfield had worked in its Information Systems department on a short-term contract.
"There was no evidence that he was doing anything untoward," a spokesman said.
The allegations against Mr Benfield came to light following an investigation by the Sunday Telegraph newspaper.