Pacific Ethanol Inc said on Tuesday that its first-quarter sales had fallen by nearly half and warned again that it would need to file for bankruptcy protection if it could not soon restructure its debt.

In a filing to the U.S. Securities and Exchange Commission, Pacific Ethanol said sales fell 46 percent to $86.7 million in the quarter from a year earlier. It estimated that its net loss for the period had narrowed to $23.9 million from $35.2 million.

Pacific Ethanol, like other makers of the corn-based biofuel, has struggled as weak U.S. demand for motor fuels has depressed prices and margins.

VeraSun Energy, once the largest publicly listed U.S. ethanol maker, filed for bankruptcy protection last year and has sold off most of its assets.

In its filing, Pacific Ethanol said it had been actively pursuing alternatives to try to restructuring its debt, including raising additional debt or equity financing.

However, there can be no assurance that the Company will be successful, it said. If the Company cannot restructure its debt and obtain sufficient liquidity in the very near-term, the Company will need to seek protection under the U.S. Bankruptcy Code.

Its volume of ethanol sold fell 24 percent in the quarter, the company said, while the average sales price was down 28 percent.

Shares of Pacific Ethanol were down 2.8 percent at 70 cents in morning trading. They had hit a low of 20 cents in early March.

(Reporting by Matt Daily; Editing by Lisa Von Ahn)