"Unless this trend is halted, the banks are headed for a crisis," party spokesman Malesela Maleka said in a statement.
Maleka was backing comments made on Friday by party general secretary and Higher Education Minister Blade Nzimande.
"The South African banking industry is developing towards a huge crisis, likely to lead to a serious bubble, not dissimilar to that of the rest of the global banking and financial sector, unless drastic action is taken to prevent this," Nzimande wrote in the SACP newsletter, Umsebenzi Online.
He attributed this to South African banks changing their lending patterns from 2008.
Unsecured lending refers to debt for which the borrower does not have to provide any form of security, such as credit card debt.
Finance Minister Pravin Gordhan told the Foreign Correspondents' Association in Johannesburg yesterday that there was "no crisis in the banking system".
He said the banking sector was one of three which had withstood the financial crisis. The others were India and Australia.
Gordhan admitted that there had been a change in lending patterns.
He said it was not clear by how much unsecured lending had grown, as figures from various organisations differed, but it had significantly increased.
"If it feeds into consumption rather than investment, then that is a worrying sign." Gordhan said that, according to some reports, higher income groups were taking chances with their levels of indebtedness.
Banking Association SA MD Cas Coovadia said yesterday that he was extremely concerned about Nzimande's statements.
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