Sir Christopher said his committee may carry out its own probe
Standards watchdog Sir Christopher Kelly has said the Commons' attempts to block the release of a breakdown of MPs' expenses is "unfortunate".
Sir Christopher told the BBC the High Court appeal against a tribunal ruling made it look like there was "something to hide".
But he accepted there were security concerns over releasing MPs' addresses.
He pledged to launch his own inquiry into MPs' expenses, if he is unhappy with the outcome of an internal review.
The Commons authorities have appealed to the High Court over a ruling it publish details of 14 MPs' second homes allowance claims.
They argue MPs' addresses should not be published but it is not known if that is the sole basis of the appeal.
Attempts to question the exact nature of the appeal have been rejected by Speaker Michael Martin, who told MPs they could not discuss it in Parliament as the case was now "sub-judice".
No date has yet been set for the High Court hearing.
Speaking to the BBC about MPs' expenses, Sir Christopher said: "What has fuelled distrust is the notion that so much of this is conducted in ways that are less than fully transparent."
The chairman of the Committee for Standards in Public Life said he expected the MPs' own review into expenses to be bold, and said he had no reason to think the Speaker, Michael Martin, did not understand this.
But he added: "On the other hand, the decision to appeal against the Freedom of Information decision, about disclosure of expenses, was an unfortunate one in this context because it does suggest that there is something to hide."
He said it was unfortunate MPs feared revealing their addresses - something ordered in the FOI request - but he accepted it was a "real issue" for a number of MPs and it "would be unwise" to entirely discount it.
He denied there was any pressure on his committee not to carry out its own inquiry into MPs' expenses but said he thought it would have been "much better" to do an independent inquiry - similar to that carried out by Sir Alan Langlands for MSPs.
He said: "I can't think of any other circumstances of this kind in which people would set up a group of self interested individuals to review their own pay and allowances. I think that's the main problem."
He said it meant its public credibility would be affected, whatever the outcome and said his committee might yet carry out its own inquiry.
"We have been absolutely clear that if the outcome of the inquiry is not satisfactory, we will do one of our own," he said.
In January the Commons authorities lost a Freedom of Information Tribunal case, and was ordered to publish detailed breakdowns, with receipts where possible, of 14 MPs' claims under their Additional Costs Allowance.
MPs can claim up to about £23,000 a year each under the allowance, which covers the cost associated with an MPs' second home.
The Commons was told to publish the details by 25 March, but on that day it announced it would be appealing to the High Court - arguing if MPs' addresses were published it could compromise their security.
Several MPs have complained that the details should have been published - Lib Dem leader Nick Clegg described the decision to lodge an appeal as "a needless, additional hammer blow to public confidence".