A spat between the London Stock Exchange and the US Securities and Exchange Commission loomed yesterday after Roel Campos, an SEC commissioner, described London's junior Aim market as a casino on which30 per cent of listings were "gone within a year".

The LSE hit back, declaring Mr Campos's reported failure rate an exaggeration by a factor of about 10 and hinted that jealousy over Aim's success in attracting US listings lay behind his comments.