David Blunkett's spokesman has brushed off as an "administrative error" an apparent breach of parliamentary rules.
Mr Blunkett said he had made an 'honest mistake'
The work and pensions secretary used House of Commons headed notepaper to object to a building development near a property he owns in London.
He wrote to Wandsworth council saying he was "deeply concerned" by the plans.
The spokesman said: "The letter was dictated to his office. It was never his intention that Commons stationery be used. This was an honest mistake."
He added that Mr Blunkett wrote expressing concerns about its environmental impact after being approached by local residents.
"He did so as an ex-resident who knows the area well... in retrospect, Mr Blunkett recognises he should have explicitly specified that the letter went on plain paper, which is what he always intended," the spokesman added.
The House of Commons official who regulates the use of MPs facilities, the Sergeant at Arms, says no complaint has been received about the matter.