The head of South Canterbury Finance says the company will struggle to meet a cash target set by its credit rating agency, despite another big cash injection from South Island businessman George Kerr.

Mr. Kerr is stumping up another $15.5 million for the company,  taking his total investment to $37.5 million.

The global credit rating agency Standard and Poor's says it may downgrade South Canterbury's BB rating, by a notch or more, if it fails to boost its cash balance to at least $150 million by the end of May.

South Canterbury Chief Executive Sandy Maier says the cash balance is tracking between $80m and $100m at the moment and meeting the target will depend on collections in the coming days.