The Bank of England said the availability of credit for companies increased for the first time in a year in the last three months of 2012, when lenders also reported a big jump in the supply of secured loans for households.
With a further increase in credit expected in the current quarter, the results of the bank's latest Credit Conditions Survey point to a marked improvement in conditions in funding markets.
They may indicate the latest official effort to encourage banks to make more funding available, through the Funding for Lending scheme, is having an effect.
The Bank of England said: "The Funding for Lending Scheme was widely cited as contributing towards the increase in secured and corporate credit availability."
Introduced in August, the Funding for Lending Scheme allows banks to access reduced rate official funding.
The survey also found evidence that banks have cut the cost of the funding they provide for successful applicants.
But the findings are unlikely to allay persistent concerns that small businesses are struggling to access affordable funding,
Banks reported only a slight increase in credit availability for small firms.
Profit margins, or spreads, on lending narrowed significantly for large and medium-sized firms but remained "broadly unchanged for small firms".
Lenders reported demand for credit fell among small firms.
Dr Adam Marshall, director of policy and external affairs at the British Chambers of Commerce (BCC), said: "In our view, this reflects discouraged demand among small businesses, with recent BCC research revealing that half of firms mistrust banks and building societies."
Howard Archer, chief UK economist at IHS Global Insight, said: "Given that it is a lack of available and affordable credit to smaller companies that has been of particular concern, it is slightly worrying to see that it is the smaller companies that appear to be benefiting the least so far.
"The main impact of the FLS to date appears to have been in lifting the amount of credit made available to households for mortgages."