The U.S. secretary of state, Condoleezza Rice, will fly into a storm of criticism Monday as she begins a four-country swing through Europe amid mounting outrage over allegations that the United States has conducted covert counterterrorism missions on the Continent.

Accusations that the United States has snatched terrorism suspects from European streets, operated secret detention facilities, and used airports as stopover points for CIA planes transferring captives have caused a furor.

The charges have provoked parliamentary inquiries, caused close U.S. allies to issue indignant demands for information, and triggered a spate of criminal investigations.

Most of the allegations are speculative, but they have made for shrill headlines from Portugal to Poland in recent days and stoked anti-U.S. anger on the Continent to levels not seen since the invasion of Iraq.

The European Union's top justice official warned last week that any member state found to have permitted secret U.S. jails on its territory could be stripped of its voting rights in the organization.