The New York State Department of Financial Services (DFS) may have blocked Barclays from joining a group settlement involving five other big banks for currency market manipulation, according to insiders cited by Reuters.
Since the DFS regulates Barclays but not the five banks which settled with other regulators in the UK and the US, this presents the British lender with a set of issues, reported Reuters citing three unnamed sources.
The sources said that the DFS could have blocked Barclays joining in on the group settlement, which the New York regulator labelled as "weak".
Barclays may have pulled out from the group settlement because if it admitted wrongdoing the DFS could strip the bank of its NY banking licence - which is it has threatened to do so to other banks in the past.
Barclays said in a statement that the bank had "engaged constructively with the Financial Conduct Authority (FCA) and the US Commodity Futures Trading Commission (CFTC) and considered a settlement with them on terms similar to those agreed by other banks."
"However, after discussions with other regulators and authorities, we have concluded that it is in the interests of the company to seek a more general coordinated settlement."
Barclays declined to comment further on the Reuters report.
On 13 November, the FCA and CFTC fined five banks - Citibank, HSBC, JPM, the Royal Bank of Scotland (RBS) and UBS - a combined total of $3.4bn (£2.1bn, €2.7bn) for their role in the manipulation of the foreign exchange market.
Other authorities have hit a number of these banks with extra penalties.
Citi has confirmed that it will pay around $1bn in fines to three separate authorities after the Office of the US Comptroller of the Currency (OCC) hit the group with another $350m fine.
Meanwhile, the Swiss Financial Market Supervisory Authority (Finma) also concluded enforcement proceedings against UBS and ordered the lender to disgorge a total of $139m.
It has also initiated enforcement proceedings against eleven people involved in the case.
The US Federal Reserve has since confirmed that it is investigating a number of unnamed banks for improper conduct around the currency markets and is working with the Department of Justice and overseas authorities.