Investor lending accelerated to its fastest growth since the bank regulator APRA imposed tough restrictions to slow down lending at the riskier end of the property market.

Key points: Investor lend grew at 27.5 per cent year-on-year in January

Investor lend grew at 27.5 per cent year-on-year in January Fastest growth since APRA imposed 10 per cent speed limit in 2014

Fastest growth since APRA imposed 10 per cent speed limit in 2014 First home buyer lending continues to decline

Australian Bureau of Statistics figures show investor lending grew at a seasonally adjusted 27.5 per cent over the year to January, almost three times the 10 per cent speed limit imposed on the banks in late 2014.

It is the fastest growth since August 2014 and comes on top of another heady month in December where investor mortgage growth came in at just under 20 per cent.

Owner-occupier lending came in at a far more modest annualised pace of 1.9 per cent, and when refinancing is stripped out actually fell by 1.5 per cent.

"The recent acceleration in investor activity is sure to keep both the RBA and APRA on high alert, as market sentiment shows no signs of easing," ANZ economist Daniel Gradwell said.

The January figures pre-date the moves by a number of banks — particularly Australia's biggest lender, the Commonwealth Bank — to throttle back on the investor sector last month.

The Reserve Bank this week was more muted in language about the success the APRA speed limit was having saying that the "supervisory measures have contributed to some strengthening of lending standards".

Previously the RBA had said APRA's measures had "strengthened" lending standards in the sector.

Investor appetite for property has shown a marked resurgence over the past six months, since tumbling in mid-2015.

Westpac's Matthew Hassan said the January figures suggest lenders will either have to start reining in growth in investor loan approvals back to a sub 10 per cent annual pace in coming months or run the risk of sanctions from the regulator.

APRA has warned the banks if they breach the speed limit they may be required to hold higher levels of top tier capital, which would lead to a drag on profitability.

"While the growth rate in the stock of investor debt remains below APRA's 10 per cent limit, further results like today's are likely to see growth nudge closer over coming months," Mr Gradwell said.

First home buyer commitments continued to fall in January, both in dollar terms as a percentage of total lending.