Hong Kong,  China's embattled property giant Evergrande has failed to deliver a preliminary debt restructuring plan it had promised by July 31, leading to further concerns about the future of the world's most indebted developer, media reports said.

The real estate company's failure to meet its self-imposed deadline comes at a time when China's entire property sector is dealing with a growing mortgage boycott and slumping housing sales, CNN reported.

According to an exchange filing on Friday, Evergrande offered instead some details on "preliminary restructuring principles" for its offshore debt, and said it aims to announce "a specific offshore restructuring plan within 2022."

Evergrande, China's most indebted developer with $300 billion in liabilities, has been at the heart of the country's real estate troubles since last year. It defaulted on its US dollar bonds in December after scrambling for months to raise cash to repay creditors, suppliers and investors, CNN reported.

To contain the fallout, the Chinese government has intervened to take a leading role in guiding the company through a restructuring of its debt and sprawling business operations.

In Friday's filing, Evergrande said it has made "positive progress" in its offshore restructuring process, but added that it's still working with creditors and advisers on conducting a due diligence of the company.

"Given the size and complexity of the Group and the dynamics the Group finds itself in, the due diligence process remains ongoing," it said, adding that the work might be completed in the "near future."