In a statement, the Swiss-based firm said the revolving credit lines were "critical" for business.
Petroplus shares fell as much as 40% on Tuesday and have lost 83% since the start of the year.
It said it was "evaluating strategic options" in order to try to maintain its refining and marketing operations.
Demand for fuels has weakened in the sluggish global economy, cutting profits and leading to temporary closures, sales and conversion of refineries into storage sites.
Analyst firm Vontobel Holding AG said: "We strongly advise investors to stay clear of the stock until a sustainable financing can be restored."
