The Danish presidency of the EU said the European Commission and Switzerland remain at odds over banking secrecy following talks yesterday.
A Danish official said the lack of progress in the negotiations over the EU's intention to tax interest on non-residents' savings means "the prospect of an agreement immediately is not very likely".
EU taxation commissioner Frits Bolkestein will brief EU finance ministers on the outcome of the talks between commission and Swiss officials at their informal meeting in Copenhagen from Friday.
The Danish official said no resolution to the long-running disagreement is expected at Copenhagen, but he expects a showdown at the ministers' October or November meetings.
EU countries intend to bring in an information exchange system, though initially Luxembourg, Belgium and Austria would be allowed to run a withholding tax for a transitional period. The Swiss have rejected information exchange.
The commission aims to reach agreement with non-EU countries like Switzerland and the US on savings taxation by the end of the year.
Bolkestein will also report to ministers on negotiations with the US.