TSB Bank has launched a fresh volley in the mortgage war, offering what's thought to be New Zealand's first 10-year fixed-rate home loan.

The rate is set at 5.89 percent, and loans are available for residential and investment property loans - provided buyers can stump up a 20 percent deposit.

BNZ's seven-year fixed home loan, at 6.89 percent, is the next longest term offered by a bank.

The 5.89 percent rate of TSB's new offer is matched only by Kiwibank's five-year home loan deal.

Meanwhile homeowners across the Tasman could be in line for another interest rate cut.

Treasurer Joe Hockey believes the RBA could slash the cash rate again, after it came down to an all-time low of 2.25 percent this week.