London mayor criticised over release of transport figures
Boris Johnson has been criticised for releasing figures showing a drop in crime on London's public transport, ahead of their official publication.
The UK Statistics Authority (UKSA) said City Hall's decision to send out the press release was "poor practice".
It was based on quarterly figures from Transport for London (TfL) but was put out "some time ahead" of its official publication, the UKSA said.
The mayor said the data was accurate and used to reassure the public.
The UKSA's chairman Sir Michael Scholar said Mr Johnson did not break the law as TfL figures were not classified as official statistics - something he said he would ask the Cabinet Office to change.
'Code of Practice'
In a letter to the mayor he said: "Whatever their answer, I believe that selective prior release, as in your press release of February 21, was poor practice, and was damaging to public trust in the statistics produced by Transport for London.
"In the interests of restoring public trust in Government statistics, may I invite you to undertake in future to comply with the Code, as a matter of principle?".
The UKSA's Code of Practice says statistical reports should be published "separately from any other statement or comment about the figures", that "no statement or comment - based on prior knowledge - is issued to the press or published ahead of the publication of the statistics".
It also states that "no indication of the substance of a statistical report is made public or given to the media" prior to publication.
'Seek to reassure'
A spokesperson for the mayor said: "Londoners will understandably want to know how safe their transport system is and the mayor will always seek to reassure them."
He said the accuracy of the figures had not been questioned and the use of the statistics was not subject to the regime suggested by Sir Michael.
However, he added, they would happy to look at the suggestions made.
The letter from Sir Michael came in response to a complaint about the press release by Full Fact, a group which says it campaigns for accuracy in public debate.