"The US Government has informed the Court in the John Doe Summons matter that the parties have reached an agreement in principle on the major issues and expect to resolve the remaining issues in the coming week. A status conference among the parties has been scheduled for August 7, 2009," UBS said in a statement.

"At the request of the US and Swiss Governments, we have agreed not to comment further at this time," the bank added.

The US Justice Department and US Internal Revenue Service did not immediately comment when contacted by WealthBriefing. 

A settlement may be submitted in writing on 7 August, Justice Department attorney Stuart Gibson was quoted by Bloomberg as saying on a telephone conference call. No details of the accord were provided, the report said.

“The parties have reached an agreement in principle on the major issues,” Mr Gibson was reported to have told US District Judge Alan Gold. “There are a couple of minor issues that need to get resolved. We expect to be able to resolve them in the coming week.”

The US tax and law authorities have been attempting to make UBS, until recently the world’s biggest wealth manager, to hand over details on thousands of its clients. Traditionally, Swiss banking law forbids any Swiss bank from disclosing such data. Tax evasion, while a crime in countries such as the US and UK, is not recognised as a criminal offence in the Alpine state.

Although reports have said US authorities are seeking details on up to 52,000 account holders, some reports have said the figure is far lower than this.

In a fresh twist to the woes of Swiss banks in the US, media reports have said that US federal prosecutors have widened their investigation into banks suspected of selling offshore tax evasion services to wealthy US citizens. The probe now includes a small private bank in Zurich.

Bloomberg said that any settlement will avert the need for a two-day evidentiary hearing that Judge Gold planned to begin on 3 August.

UBS has already agreed to pay the US a total of $780 million to defer prosecutions after it admitted helping US clients evade taxes. However, the firm has so far stood fast on granting the US Internal Revenue Service access to thousands of UBS’s client details.

In rankings provided by Scorpio Partnership, the wealth management consultancy, UBS was supplanted by Bank of America-Merrill Lynch as the world's largest wealth management firm, although internationally, UBS is still the world's largest firm in this sector.