Westpac has swung the axe on a range of alternative mortgages marketed by its Bank of Melbourne and Bank SA subsidiaries.In identically worded memos sent to mortgage brokers on Tuesday, BoM and Bank SA announced that their fixed and variable rate low doc home loans would be withdrawn from sale on 1 July.BoM and Bank SA will also exit the reverse mortgage market aimed at senior borrowers, binning a range of 'Seniors Access' mortgages at the end of the week.The subsidiaries told brokers that the decision to rein-in unconventional lending followed strategic reviews of products and services.The product withdrawals coincided with separate moves by Westpac to tighten lending policies for property investors and self-managed superannuation super funds.Westpac's broking unit outlined the following policy changes that will also apply to BoM and Bank SA mortgages: from 26 June self-managed super funds taking out an interest-only loan will have the maximum repayment term reduced from ten years to 5 years; an SMSF with less than $200,000 of liquid assets will be ineligible for an interest-only mortgage; from 1 July Westpac, BoM and Bank SA will introduce new serviceability assessments before home borrowers with standard home loans can switch to interest-only terms; and switching from any loan product into an equity access loan will require brokers to undertake a loan re-origination.The stricter lending policies come after Westpac and its three main subsidiaries - Bank SA, St George and Bank of Melbourne - posted sector-leading growth in the investor market this year.According to data published last week by AFG, the country's biggest mortgage aggregator, Westpac-owned brands accounted for one third of all investor mortgages sold by brokers in April and May.Westpac's nearest rival in this segment of the mortgage market has been ANZ, which is accounting for 15 per cent of AFG sales.The country's largest home lender, CBA, accounts for ten per cent of investor loans originated by AFG brokers.While all the major banks have increased rates on interest-only loans several times this year, Westpac's strong growth in investment lending may have forced it to toughen eligibility criteria to satisfy the prudential regulator.In March, the Australian Prudential Regulation Authority threatened to intensify supervision of bank lenders unless they limited the flow of interest-only lending to 30 per cent of new mortgage business.In the memos sent to brokers, Westpac and its subsidiary brands appeared to send a strong signal that the group planned to curtail lending to investors for the rest of the year. Bank of Melbourne told brokers that the changes were attributable to "regulatory requirements"."These changes will help us continue to meet our regulatory requirements and apply responsible lending practices in assessing a customer's ability to service existing and proposed debts," BoM stated in its memo.Westpac stated in its memo that the changes would "help us protect the interests of our customers and ensure we continue to meet our regulatory requirements".St George is yet to communicate any changes to lending policies to brokers.