Birmingham's Labour councillors are seeking legal advice in a bid to stop their numbers being cut by 20.

The Labour group voted in favour of launching a legal challenge to last week’s announcement by the Local Government Boundary Commission that there are too many of them.

The commission said that the number of councillors in Birmingham should be cut from 120 to 100 and is spending the summer asking residents and politicians for their views on new ward boundaries.

But there is much opposition from councillors who, apart from feeling personally endangered by the cut, argue that they already represent the largest wards in the country – with an average 9,000 residents each. This ratio will increase to 11,000 each after they are cut in 2018.

Council Labour leader Sir Albert Bore, who told the commission not to cut below the 100, urged his colleagues to accept this number during a private group meeting. He said they have to accept a more ‘streamlined’ council.

But he was voted down by backbenchers who said they wanted to seek legal advice over whether it would be possible to mount a challenge in the courts.

The cost of this legal action would come from the Labour Party, not the council or taxpayer.

One councillor said: “Members felt they should not roll over and take this.”

Last week long-serving Labour councillor Carl Rice (Ladywood) explained why many are aggrieved.

“We are expected to deal with issues strategically and locally. So we are having to deal with the work of representing the public and running the largest local authority in Europe,” he explained.

He added that increasing workloads in some of the most deprived parts of the country would also make it more difficult for people to hold down jobs and sit on the council, something which keeps members ‘grounded’ in the real world.

There are 77 Labour councillors, but it is understood that only 45 to 50 were at the meeting due to holidays.

Opposition Conservatives have argued in favour of keeping the 120 councillors, while the Lib Dems have argued that more local councils, such as the new one being established in Sutton Coldfield, could make up for the shortfall.

The reduction was in line with one proposed by government troubleshooter Lord Bob Kerslake in his damning report last year which found the city council crippled by poor quality of leadership and governance.

The Boundary Commission argued that new arrangements would increase the effectiveness of members, even though their number is being cut.