The Competition Commission is extending the scope of its look into small business lending practices by banks and building societies.
The watchdog is now sending questionnaires to banks and building societies not involved in lending to small business as it attempts to explain why the big four high street banks have such a stranglehold over the market.
Lengthy surveys have already been sent out to the big four banks, RBS-owned NatWest, Barclays, Lloyds TSB and HSBC, asking them about their lending practices.
The four banks control 83 per cent of the small business lending in the UK.
Alliance & Leicester and Abbey National have recently announced plans to dive into the small business lending market in attempts to offer up a challenge to the larger banks.
The banks will be summoned before the Competition Commission for an open-session hearing on September 8.