Banks have been warned to treat their customers fairly or feel the might of the Financial Services Authority.

FSA managing director of retail markets Clive Briault told the British Bankers' Association conference tougher enforcement or detailed regulation would be the consequences of not treating their customers fairly.

He acknowledged the work that had been done by many firms to improve customer service but added: "We have seen cases of firms developing products without assessing which consumers these products are likely to be suitable for, which consumers they are not likely to be suitable for, and how the products are likely to be sold and advised upon in practice.

"If firms do not embrace the principle of treating customers fairly, we will reconsider how best to achieve the fair treatment of customers, be it through the introduction of ever more detailed rules or tougher enforcement action."