Director Robert Sinclair said: "The turbulence in the financial markets has had a major impact on the mortgage market and consumers’ access to finance.
"The consolidation of the market and government intervention has led to the creation of four banking groups who control around 80% of the current account market and six groups who are responsible for around 90% of mortgages written.
"This concentration, under any economic definition, is a major restriction on competition and is ultimately bad news for consumers.
"We disagree with the conclusion of the Treasury report that the key characteristics of competition in the mortgage market have not been affected.
"We need to see an increase in the number of lenders or at least increased levels of lending among those in the market. Without this, consumers, and particularly first-time buyers, will find it increasingly difficult to enter the housing market, which would stifle a recovery."
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