George Osborne has been reprimanded for launching a think tank without consulting the ex-ministers’ lobbying watchdog.
The former chancellor launched the Northern Powerhouse Partnership in September, to “push and fight for” ideas he championed when in government.
But the Advisory Committee on Business Appointments said it should have been consulted beforehand.
The committee advises ex-ministers on taking up jobs after they leave office.
Rules prevent ministers from lobbying government for two years after leaving office. and there are restrictions on the jobs they are able to take up during this time.
Mr Osborne’s role is unpaid and the Northern Powerhouse Partnership is a not-for-profit organisation.
In a letter to Mr Osborne, the advisory committee said government departments had not expressed concerns about him taking on the job, but added: “The committee noted with concern that you sought advice on this appointment after you had launched the Northern Powerhouse Partnership.
“The committee is unable to offer retrospective advice on appointments that have already been announced.”
It told Mr Osborne he should not use “privileged access” gained from his time as a minister to influence government policy.
“The committee would also remind you that advice should be sought on all appointments, paid or unpaid, before they are taken up or announced,” it added.
The Northern Powerhouse Partnership – described as an independent group of politicians, business people and civic leaders – has recruited the former mayor of New York, billionaire businessman Michael Bloomberg, to advise the powerful new elected “metro” mayors being created in city regions including Manchester, Liverpool and Sheffield.