Lenders are tapping into an unusual source of deposits to fund their lending activities. Superannuation contributions are being channelled through the wealth management arms of banks and life companies via cash account and term deposit options into their lending businesses.AMP reported yesterday that its banking business received 34 per cent of its funding from retail deposits, 46 per cent from wholesale funding and 20 per cent from superannuation contributions.An AMP spokesperson said the bank invested cash deposits on behalf of AMP, in the form of mortgage sales. With the big increase in retail funds being directed to cash accounts and term deposits this year, these funds have been an important funding source.This may be a factor in AMP Banking's strong mortgage lending growth over the past six months. The mortgage book has increased from $8.1 billion at the end of last year to $9.1 billion at the end of June - a 24.7 per cent annualised growth rate.Other lenders to report strong increases in funding from super contributions include St George, through its wealth management arm Asgard, Westpac through BT Super and ANZ through ING Australia and some third-party deals.St George Bank reported at a market update earlier this month that it had grown its retail deposit book by almost 19 per cent to $55.3 billion over the past year and in the process has been able to reduce its demand for funds from other sources.Until two years ago investors on the Asgard platform who wanted a cash portfolio option were given a choice of third party providers, such as Macquarie Cash Management Trust. Asgard added a St George wholesale cash option and the bank has picked up around $2 billion of deposits through the Asgard channel since then.BT Wrap, the superannuation investment platform of Westpac's wealth management division, reported yesterday that it has taken $1 billion in term deposit applications in the four months since it launched a term deposit option on the platform.The three and six month, and one and two year terms on the platform are provided by Westpac. BT said about one third of term deposit funds had come in as new money, with the remainder coming from investors switching from other asset classes.Some analysts doubt the quality of this new funding source on the grounds that banks count super contributions as retail deposits but in reality the internal transfer mechanism that got the money from the super fund to the bank was a wholesale transaction.In other words it is expensive wholesale money that provides a low margin.The banks dispute this. In June, ANZ launched a cash management account, the Prime Cash Management Account, that sits within Russell Investment Group's Private Active Pension.It is common for super fund members with retirement income options to draw down pension payments in lump sums on a periodic basis and put the money into a cash account until it is needed.The appeal of the Russell offering is that the ANZ cash account sits inside the super fund, so that interest