The banking sector has to be referred to the Competition Commission.
Which? chief executive Peter Vicary-Smith feels the dominance of the big lenders has to be broken up in order to encourage the creation of more institutions.
He was speaking after Labour leader Ed Miliband stated at least two new banks should be set up by 2015, with the big five - Royal Bank of Scotland, Barclays, Lloyds, HSBC and Santander - forced to sell off some of their branches.
Mr Vicary-Smith observed the proposed ring-fencing between investment and retail banking should also be brought forward - it is currently due to be completed by 2019.
He also called for "tangible action on tackling the corrosive banking culture to turn this sector into a profession we can all trust again".
The expert went on to note it is already one year since the Vickers' report into banking was produced and not enough action has been taken from its recommendations.
By Asim Shah