This is according to the International Monetary Fund (IMF) said this in a report about banks operating across African borders.
The Fund said Ecobank Nigeria's "relatively weak capital position remains a concern" and that rapid loan growth at the bank, which is a subsidiary of Ecobank Transnational Incorporated, raises suspicion of reckless lending.
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A bank spokesman said that much of what the report said about Ecobank appeared to refer to events of last year, when the bank fired its chief executive Thierry Tanoh after months of turmoil over corporate governance.
"Ecobank has put in place robust structures to ensure its corporate governance," said spokesman Richard Uku.
Ecobank is one of the largest financial institutions in sub-Saharan Africa and has a presence in 36 countries on the continent. Its assets in 2013 stood at 22.5 billion dollars, according to the company's website.
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The bank is appealing a court decision last month in Ivory Coast to award Tanoh 15 million dollars for defamation over a letter written prior to his dismissal. It is also appealing a Togolese court's award of 11.6 million dollars to Tanoh for unfair dismissal.