The ECB's move will encourage banks to create more such securities, since they could use them to get credit themselves from the central bank at its regular offerings.
The bank made the move, even though it has long stressed that other European Union institutions, such as governments, have a major role to play in further loosening credit in the parts of the eurozone hardest hit by the currency union's financial crisis.
Beyond Thursday's measures, the ECB is also in talks with the European Investment Bank on further steps to encourage a market for asset-backed securities as a source of credit for small and medium sized businesses. One possible measure could be EIB guarantees for the packaged loans, which would raise their credit ratings and enable a broader range of investors to buy them. The EIB is backed by eurozone taxpayers and run by their governments.
The ECB said in its statement Thursday that it would now accept asset-backed securities with A ratings from at least two ratings agencies, instead of requiring two AAA ratings.
The ECB also said it would give out more credit on each eligible asset-backed security that banks use as collateral to get loans. To protect itself from losses, the ECB does not hand out 100 cents of credit for every euro of collateral, but deducts a percentage known as a haircut as insurance. Haircuts can range from tiny slices such as a 0.5 percent haircut on short-term, safe investments to 44 percent when it loans against longer term, less secure securities.
The bank also said it is looking at accepting even lower-rated kinds of asset-backed securities known as mezzanine tranches.
Although such steps in theory increase the ECB's risk of loss, it said it was balancing that by restricting the use of other kinds of asset-backed securities known as covered bonds.