The Irish Small and Medium Enterprises Association (ISME) says securing the payment of overdue debts is becoming a growing problem for many businesses.
The association says its members are currently waiting an average of 69 days to be paid by their debtors.
It says one-third of firms are experiencing delays of more than 90 days, an increase of 28% since last December.
ISME says such late payments are strangling small businesses.
"The result of this is, at the very least, an increase in unnecessary administrative burdens and, at worse, is leading to insolvency," said ISME chief executive Mark Fielding.
"These large companies create a double bind for small companies who are only in a position to make payment once they themselves have been paid. This abuse of a dominant position amounts to an ‘interest free loan’ which SMEs are obliged to give to their much larger and economically stronger customers.
"The result of this is that the smaller businesses have to seek increased facilities from their banks who are not releasing funds, as detailed in previous ISME research, and so businesses are closing down, not due to lack of profits, but due to lack of cash."