Philip Hammond has responded to a newspaper sting by The Sunday Times.
He told the The Andrew Marr Show: "I think the revelations are deeply damaging to the individuals concerned and their reputations.
"There is no way that retired officers influence the way in which military equipment is procured.
"I am satisfied that the system we have is completely robust.
"But there is an issue. Firstly over whether any rules have been broken. Clearly at least one, possibly more of the individuals named in The Sunday Times piece were still under the terms of the two year restriction that applies after they have left the service.
"Secondly we have to look at the level of access that we give retired officers to the MoD and to serving officers. "
More top news
The President-elect was named Time's person of the year for creating a "Divided States of America".
Children and young people with terminal and life-limiting illnesses should be asked whether they have a bucket-list they wish to complete.
Warning lights and barriers were in place to warn drivers the bridge was closed but the band still drove through, an inquest heard.