Matt Comyn, CBA's head of retail banking, said the bank has not breached the limit since it was announced in December 2014 and remained "focused on meeting our regulatory commitments".

New investment loans account for about 35 per cent of its lending book and 33 per cent of new mortgage business, according to the bank. The bank loan book does not identify how many investment loans are transferred from other lenders.

The move could result in smaller lenders receiving a flood of investor loan applications, causing other lenders worried about breaching speed limits to also cut back lending.

"We need to ensure we continue to meet our commitments," the document to be sent to mortgage brokers claims.

"We are committed to consistently delivering the best customer experience for home buyers, upholding the highest level of professional standards and meeting our responsible lending and regulatory obligations."

Details about the length of the suspension - or what happens to loan applications between now and next Monday - are not available.

Loan transfer applications between today and next Monday are expected to be reviewed on a case-by-case basis.

The announcement comes less than 24 hours after its subsidiary, BankWest, announced that it was also toughening lending conditions for investment loans after details were revealed by The Australian Financial Review.


CBA's half-year results on February 15 could provide more insights into group lending volumes.

About 1.5 million Australian households have an investment property and the number of investment loans is rapidly increasing, particularly in Melbourne and Sydney.

According to the latest government analysis, December's investment loans grew at 0.8 per cent, twice as fast as owner occupied loans and accounted for about 36 per cent of all loans for investment purposes.

Last month the bank announced rates rises of up to 15 basis points for investor loans. It also closed a popular loophole used by property investors to switch from principal and interest loans to interest-only, which require lower monthly repayments because principal payments are deferred.

Mr Comyn, chief executive for retail banking, flagged concerns about rising wholesale funding costs and the need to remain below the 10 per cent speed limit.