Guarantees must be made that the London Stock Exchange will not find itself under the auspices of the Securities and Exchange Commission if the market is bought by Nasdaq or the New York Stock Exchange, according to brokers.

Angela Knight, chief executive of private client broker Apcims, said the SEC must avoid investigating the affairs of UK businesses listed on the LSE if the exchange is acquired by a US equivalent, reported the Daily Telegraph.

She is concerned with the difference in US and UK accounting standards, plus the onerous affect on US business of Sarbanes-Oxley legislation.

However, FSA chief executive John Tiner recently suggested that the SEC would not get involved in UK companies listed on the LSE, if the exchange was acquired.