US Attorney General Eric Holder met with his counterpart from Switzerland as investigators crack down on Swiss banks that help US customers avoid paying taxes.
US officials were tight-lipped about the content of the meeting between Holder and Eveline Widmer-Schlumpf, but told AFP that the US probe into the Credit Suisse bank was discussed.
Credit Suisse has been in talks with the Justice Department to settle a probe over its role in enabling Americans evade taxes. US prosecutors have reportedly pressed for a guilty plea from a bank subsidiary.
One possible outcome is that Credit Suisse will be fined. Press reports say the fine could exceed the $780 million that another Swiss bank, UBS, paid in 2009.
In early April Credit Suisse said it had set aside 425 million Swiss francs ($476 million) in provisions for a possible deal with US tax authorities.
The Justice Department has described a decades-long conspiracy that resulted in secret accounts for US customers.
"The conspiracy dates back to 1953 and involved two generations of US tax evaders including US customers who inherited secret accounts" at Credit Suisse, it said in a July 2011 news release.
Credit Suisse is one of 14 Swiss banks under US investigation for allegedly accepting billions of undeclared dollars from US citizens.
On Wednesday, the owner of a Swiss trust company pleaded guilty in New York to conspiring with Credit Suisse bankers to enable US customers avoid taxes by hiding assets in secret Swiss bank accounts.
Josef Dorig admitted he engaged in a "wide-ranging" conspiracy between 1997 and 2011 to help US citizens evade income taxes by concealing assets in Credit Suisse accounts held in the names of sham entities, the Justice Department said.
A US Senate report out in February showed that at its peak, Credit Suisse sheltered between $10 billion and $12 billion in largely non-reported assets in the accounts of more than 22,000 US customers.
The exact amount funds unreported to US tax authorities is probably around $7 billion, Credit Suisse director Brady Dougan in late February.