Harrow Borough Council's Independent Labour Group has announced it will not take part in an investigation into alleged racism at the authority, despite calling for the review themselves.
An independent investigation into claims of racism is being carried out by former Harrow Police borough commander Dal Babu.
In November last year, council leader Councillor Susan Hall announced the investigation into an allegation of racism, following calls from the Independent Labour group.
But today members of the group said they would not take part in the investigation because they claim the process behind it lacks credibility.
The group says other candidates were not considered to lead the investigation, which they say calls into question its legitimacy.
One member, Cllr Asad Omar said: “Our main concern is with the process with which the investigation has been carried out.
“We do not have a problem with Dal Babu but the way he was appointed is not how we understood it was going to be done."
Another, Cllr Krishna James said: “To us it seems the council have dragged their feet for five months in actually getting round to appointing someone.
“But then they give only three weeks for the investigation to be carried out. It is not enough time fully investigate issues at the council. It seems a bit of a political move just before the election.
“This is a vitally important investigation, not just for the council but also the wider community of Harrow. To us it seems as though it has not been taken seriously."
Cllr Omar added: “It is important it is done correctly and you cannot do a proper investigation in just three weeks.”
The group says it hopes Mr Babu’s investigation will lead to a second investigation which can have a thorough look at the working of the council as a whole.
A report of the investigation will be presented to the council by Mr Babu on Friday, April 11.
A Harrow Council spokesman said the authority could not comment on the investigation before it was published.