Restructuring consultancy Alvarez and Marsal confirmed on Thursday that it had withdrawn from a forensic audit of Lebanon's central bank as it had not received the information required to carry out the task.

The decision, first announced by Lebanon's caretaker finance minister on Nov. 20, is a blow to Lebanon as the audit is a key demand of foreign donors to help it exit a financial meltdown, the country's worst crisis since its 1975-1990 civil war.

"Due to the insufficient provision of information, A&M is unable to complete its review and has formally notified the Ministry of Finance of its decision to terminate the engagement," the consultancy said.

The finance minister had on Nov. 5 announced a three-month extension to secure the data required after the central bank declined to hand over all the information, citing bank secrecy.

"In meetings held on 4 and 5 November the Ministry of Finance and Banque du Liban confirmed that the information A&M requested would not be forthcoming in the near future," the consultancy said.

"We remain available should the Government of Lebanon wish to consider re-engaging A&M under circumstances more conducive to a successful completion of the mandate," it added.

The finance ministry did not immediately respond to a Reuters' request for comment.

An official source familiar with the matter said that caretaker Finance Minister Ghazi Wazni had tried to set up a meeting between President Michel Aoun and A&M to persuade the firm to continue with the contract.

Aoun has pledged to revive the audit, saying it is needed so that Lebanon does not become a "failed state". Earlier this week he asked parliament to move on the matter and the parliament speaker has set a session for Friday to discuss the issue.