BNZ chief operating officer retail Glenn Patrick said banks were licensed and required police checks on all their employees and the same rules should apply to other lenders.
Mercury's head of commercial and pre-pay credit Luke Blincoe said people who fell behind with power bills had often "got into a hole with various spurious ... operators".
"Regulation is a good step."
Salvation Army social services director Major Campbell Roberts said Mr Lotu-Iiga's bill dealt with most of the issues around loan sharks.
Four years ago, when an Auckland University study found lenders charging up to 520 per cent interest and recommended a legal interest rate cap, Labour Consumer Affairs Minister Judith Tizard rejected it.
An official discussion paper in 2009 proposed making lenders disclose more information and banning penalty fees once a borrower applied for hardship relief. But the proposals languished while Act MPs Heather Roy and then John Boscawen held the Consumer Affairs portfolio.
In May, Mr Lotu-Iiga won National Party caucus support to give at least a first reading to his Moneylenders (Licensing and Regulation) Bill, if it comes up in the ballot for members' bills.
Mr Lotu-Iiga's bill proposes that any interest rate over 48 per cent would be presumed to be "oppressive", and therefore illegal, unless a court found that it was reasonable.
Mr Lotu-Iiga's bill would require police to certify that anyone applying to be a moneylender, or to work for a moneylender, was "of good character" and "a fit and proper person".
It would also regulate fees and stop lenders taking a wide range of personal assets, such as passports and children's clothing, as security.
Proposed changes
MP Sam Lotu-Iiga's bill
* All moneylenders to be licensed and put up $20,000 bond.
* All persons working for moneylenders to be certified.
* Police reports on applicants' character.
* Interest over 48 per cent presumed "oppressive" unless good cause shown.
* Fees regulated.
* Passports, children's clothing and other listed items cannot be taken as security.