The agency, in affirming B1 and B2 ratings for the state oil venture, foresaw a "possibly tumultuous transition in civil order, economy and an already deteriorating government fiscal position."

The characteristically boisterous leader has not been heard from for weeks after undergoing his fourth surgery for an undisclosed cancer in Cuba.

Government sources have kept a tight lid on information but said the leader had been fighting a post-surgical infection, leaving loyalists and opposition alike with deep uncertainty as to the country's future.

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