London's mayor has refused to approve the nominations to the London Fire and Emergency Planning Authority as it did not adequately represent minorities.
The mayor asked the authorities to reconsider their nominations
Ken Livingstone said the nominations show "serious under-representation of women and black and ethnic minorities".
The nine nominees, five of whom are London Assembly members and four councillors, are put forward by the London Assembly and councils.
He has written to the authorities to reconsider their nominations.
Issue being 'politicised'
Mr Livingstone said: "This year's nominations offered a real chance to improve the profile of the authority and address the serious under-representation of women and black and ethnic minority Londoners but sadly this has not been acted on.
"I just do not believe that it is impossible to find more black and Asian people to serve on the fire authority, or that there are not more women who wish to participate," he added.
Mr Livingstone said he has written to Chair of London Councils, Councillor Merrick Cockell, Conservative Assembly leader Angie Bray and Liberal Democrat Assembly leader Mike Tuffrey asking them to reconsider their nominations.
Conservative Group Leader on the London Assembly, Angie Bray, accused the mayor of "politicking".
She said: "I shall be resubmitting the same names again to LFEPA. Our names are those that were considered to be the best for the job.
"I hope that it will be Mr Livingstone who will be considering his ill-judged attempts to play gesture politics with this very important body - one which oversees vitally important personal and public safety in London," she added.
There are 1,861 councillors in London, of which 555 are women and 293 come from black, Asian and ethnic minority groups.
The mayor has to appoint all 17 members of LFEPA, nine of whom are required to be members of the London Assembly and eight London Borough Councillors who are nominated by the London Boroughs acting jointly through London Councils.