State-owned Land Bank said on Thursday it was working on a new debt restructuring plan after the National Treasury declined to provide a partial government guarantee.

The country's largest agriculture-focused lender defaulted on its debt in April and has been in talks with creditors since.

It is one of several state firms that have required big bailouts that have placed huge strain on the government's finances.

The bank had intended to apply for state guarantees to partially cover planned new debt instruments.

But fiscal pressures and a government directive on the issuance of new government guarantees meant Treasury could not provide the type of guarantees it sought, Land Bank said.

It aims to finalise its revised debt plan by the end of March following the government's annual budget due in February.

It still has R4.3 billion ($284 million) in unused government guarantees which could support its new debt plan, it said.