France's foreign minister on Tuesday labelled as "unreasonable" a €7.3-billion-dollar fine the US is reportedly seeking from BNP Paribas bank on charges of violating sanctions on Iran, Sudan and Cuba.

In the first public comments by a senior French official on the high-profile case, Laurent Fabius said in a television interview that the figure sought by the US was not justified.

"If there was a fault, then it is normal that there be a sanction, but the sanction has to be proportionate and reasonable. These figures are not reasonable," he said.

Meanwhile the New York Times newspaper reported that the governor of the Bank of France, Christian Noyer, had visited New York last week to argue on behalf of BNP Paribas and to warn that such a big fine could have serious effects on the banking sector.

Noyer, who is the highest banking regulatory official in France and also sits on the policy-making body of the European Central Bank, met state and federal prosecutors in New York, the newspaper reported, citing people close to the matter.

Noyer stressed the case could have major repercussions both for BNP, the biggest French bank by capitalisation, and the global economy.

French officials are concerned that as part of a guilty plea, the bank might be forced to suspend a core business operation in New York, which could erode BNP's bottom line, the Times wrote.

It appears likely that the bank might be banned for a limited period from carrying out transactions in dollars, which could drive away part of its international client base.

Noyer was accompanied by the new French banking regulator Edouard Fernandez-Bollo who has been the head of the French prudential and control body ACPR since the beginning of this year.

Fernandez-Bollo had already visited New York the previous week but had been unable to change the attitude of the US authorities, the report said.

President Hollande has also recently raised concerns about a plea deal with the White House, the paper wrote.