New Zealand's Commerce Commission has widened its investigation into the way at least three banks lent as much as NZ$4 billion to farmers through deals based on wholesale swap interest rates.The Commission has told a parliamentary committee it has received 42 complaints from farmers who had taken out the loans at interest rates of up to 10 per cent before the collapse in interest rates in the wake of the global financial crisis. Many had complained they did not understand the loans, which locked them into high interest rates and cost the farmers millions of dollars, the Commission said.Chairman Mark Berry told the Primary Industries Select Committee that the Commission had begun its investigation in August last year and had already spent 1000 staff hours on the case."The Commission has already received a large amount of information from complainants and from [the] banks. Shortly, the Commission will widen its inquiries by seeking further information from people who have entered into interest rate swaps," Berry was quoted as saying.He said the Commission was considering whether the swap deals had been mis-sold by the banks, similar to the mis-selling scandal in the UK, which has already triggered massive settlements.Berry said such settlements were possible in New Zealand if the banks wanted to avoid being taken to court."It's going to be up to the banks as to whether they want to settle or whether they are going to stand by and let us take it to court," Berry said.Fairfax's Sunday Star Times newspaper, which has campaigned on the issue for the past six months, has said Westpac and ANZ's National Bank were the biggest sellers of the swap deals, although the Commission has not confirmed this. The newspaper cites sources estimating that as much as NZ$4 billion worth of the swap deals was sold between 2005 and 2009.