The assessment, seen by Reuters and confirmed by a government official as accurate, is the IMF's first comment on Lebanon's steps toward completing a checklist that would grant it access to $3 billion to ease the country's worst economic meltdown since the 1975-90 civil war.

The amended banking secrecy law passed in July was a watered-down version of the original proposal, prompting concerns the IMF would not consider it robust enough to qualify.

Lebanon's President Michel Aoun on Wednesday declined to sign it into law and sent it back to parliament for further changes.

On Thursday, Lebanese officials received a letter from the IMF saying the law represented "a substantial reform ... but few key deficiencies remain."

It said more government bodies should have access to banking data, including for administrative functions and not just as part of criminal investigations as the current draft stipulates.

It also said criminal liabilities for banking secrecy breaches "may have a stifling effect on detention and disclosure of criminal or suspicious activity."

The IMF did not immediately respond to a request for comment.

Now in its third year, Lebanon's financial meltdown has sunk the currency by more than 90%, spread poverty, paralyzed the financial system and frozen depositors out of their savings.

Donor states want Lebanon to enact reforms to address root causes, including decades of state waste and corruption, before releasing aid.

The IMF's staff level agreement had called for a new bank secrecy law "in line with international standards to fight corruption and remove impediments to effective banking sector restructuring and supervision, tax administration, as well as detection and investigation of financial crimes, and asset recovery."