The United States has rejected signing up to a global deal designed to settle tax evasion disagreements, according to Swiss media reports.
The SonntagsZeitung newspaper said the US authorities had written to the State Secretariat for Economic Affairs and the finance ministry informing them of their decision.
Speculation has mounted recently that the two countries were considering a voluntary disclosure scheme that would inflict fines and the handover of data in return for the US dropping legal action.
Last week, US tax investigators escalated their probe into whether Swiss bank Credit Suisse had sanctioned tax evasion practices used by some staff in dealings with US clients. They are trying to prove the bank took part in hiding some $3 billion ($2.45 billion) of client assets from the Internal Revenue Service (IRS).
Asked to confirm the existence of the letter, a spokesman for the US Department of Justice said on Monday he had no comment.
The Swiss finance ministry told swissinfo.ch on Monday it did not comment on its correspondence with the authorities of other countries.
“We are aware of the investigation that the Department of Justice has launched against Credit Suisse and we are following the affair closely. Switzerland will continue its efforts to find a solution based on existing Swiss law,” a spokesman said.