SAN FRANCISCO -- Diamond Foods Inc. will not file its Form 10-Q with the Securities and Exchange Commission before the Dec. 12 deadline for the first quarter, the company said on Dec. 12. The delay was announced as part of an update of an ongoing audit committee investigation into accounting for certain crop payments to walnut growers.

“Diamond will take steps to file its Form 10-Q for the first quarter as soon as practicable after conclusion of the investigation,” the company said. “The Audit Committee has dedicated significant resources to its investigation, including the retention of independent legal and accounting advisors, in order to conduct a thorough and expeditious review.”

Audit Committee anticipates being able to conclude its investigation by the middle of February.

Because of the filing delay, Diamond said it expects, consistent with standard Nasdaq procedure, to receive a notice of deficiency from the Nasdaq Listing Qualifications Department, indicating that Diamond is not in compliance with Nasdaq Listing Rule 5250(c)(1).

“Diamond intends to submit a plan to regain compliance as quickly as possible,” the company said. “During this process, Diamond’s common stock will continue to be listed and traded on The NASDAQ Global Select Market.”

The announcements follow the Nov. 1 disclosure by Diamond that it was investigating “external communication” in connection with the walnut purchases. The following day, the company said it was delaying its planned $1.5 billion acquisition of the Pringles snack business from Cincinnati-based The Procter & Gamble Co. until the end of June 2012. The transaction originally had been expected to close by the end of 2011.