France's foreign minister has said the reported $10bn fine being faced by banking giant BNP Paribas in the US is "not reasonable", reports the BBC.
Media reports have suggested the bank might have to pay the fine over allegations it broke trade sanctions against Sudan, Iran and Cuba.
The US Justice Department is currently looking into the claims.
French Foreign Minister Laurent Fabius said a fine of the size suggested would be "an extremely serious problem".
Speaking on the France 2 television channel, he added it would be an example of an "unfair and unilateral decision".
"The fine has to be proportionate and reasonable. These figures are not reasonable," Mr Fabius said.
His warning comes just two days ahead of Barack Obama's visit to France, where the US President is set to hold bilateral talks with French President Francois Hollande.
Mr Fabius said that if a fine of the reported scale was imposed, it would hit BNP Paribas' funds and result in fewer loans for French businesses.
"It's an extremely serious question that the Americans must handle in a spirit of partnership and not unilaterally," he added.
Read more of this report from the BBC.