Switzerland will sign a tax treaty with the US only if the Obama administration drops a legal case against Swiss bank UBS. Talks about signing a treaty were held at the weekend between the Swiss finance minister Hans-Rudolf Merz and Tim Geithener, the US Treasury Secretary. Merz indicated that the US tax authorities' investigation into UBS accounts would cause difficulties for the approval of a tax agreement in Switzerland's parliament, the FT reports. US officials say that Geithener 'understood the importance of appropriately resolving the matter' and didn't dismiss the Swiss finance minister's sentiments. Earlier in the year, UBS faced criminal charges by the Internal Revenue Service, which discovered that some of its private bankers, at a now closed off-shore banking unit, assisted wealthy clients in witholding details of valuable assets. The IRS later dropped the charges and agreed to allow UBS to settle with $780m. The Swiss bank has been forced to reveal the names of 255 US clients who used the tax evasion techniques. The IRS have now filed a separate civil case and wants to obtain information about a suggested figure of 52,000 accounts held by Americans.