The Bank of England said it would be "unrealistic" to expect to see the benefit of its Funding for Lending Scheme in August credit data it published earlier on Monday.
The FLS - which offers banks cheap finance if they increase lending to households and businesses - opened at the start of August, but mortgage lending data for the month showed an unexpected fall in net lending of nearly 300 million pounds.
"Early indications suggest the FLS is having an impact, but it is unrealistic to expect to see that in lending figures for August," the BoE said.
Last week, banks surveyed in the BoE's quarterly credit conditions survey said that they expected to make mortgages more widely available over the next three months, in part because of the FLS.
(Reporting by David Milliken)