UK financial regulators on Wednesday gave the first official recognition of intensifying City concern about the impact some overseas listings are having on the standards and reputation of London.

The Financial Services Authority said it will canvass opinions in the City about how to clarify the regulations to make clear whether companies have chosen light-touch listing methods, which can offer investors less protection. It said it was calling for formal debate about the balance between attracting new flotations and maintaining quality.

The decision comes a day after John Thain, chief executive head of the newly merged NYSE Euronext exchange group, took a thinly veiled swipe at the London Stock Exchange, criticising corporate governance and inadequate protection for minority investors offered by some Russian companies. There has been a steady flow of Russian and Kazakh companies seeking to raise capital in London.