Retail clients of BNP Paribas are keeping faith in France's biggest listed bank despite reports about a looming multi-billion fine from US regulators, the head of French retail banking Marie-Claire Capobianco said today. 

BNP Paribas may have to pay a fine of about $10 billion for allegedly evading US sanctions, sources have said. 

US authorities are probing whether BNP evaded US sanctions relating primarily to Sudan between 2002 and 2009, and whether it stripped out identifying information from wire transfers so they could pass through the financial system without raising red flags. 

BNP Paribas had French retail revenues of €1.7 billion in the first quarter, accounting for 30% of its total retail banking revenue. 

"We see support, solidarity and sympathy on the part of our customers," Capobianco said today on French media.

A $10 billion fine would wipe out projected 2014 earnings and put the bank's dividend under pressure, SocGen analysts estimated last month.

The fine would also hit core equity tier one ratio, a measure of a bank's ability to endure stress and market shocks, to go down 100 basis points from 10.6%, the analysts said. 

BNP has declined to comment on any details of discussions with US authorities but has said it is in talks with them about "certain US dollar payments involving countries, persons and entities that could have been subject to economic sanctions." 

The bank has set aside $1.1 billion for a fine, but told shareholders the penalty could be far higher than that. It has also said it has improved control processes to ensure such mistakes do not occur again. 

Capobianco added that it was important to keep BNP Paribas employees confident in the bank as well. "We need to talk to them: look what our customers are saying, look at the soundness of the bank, which is the first argument. When you live through difficult times, you come out stronger after that," she added.