Secretary of State Condoleezza Rice said Friday that the United States still has conditions for negotiating with Iran even though the Bush administration is sending a senior diplomat to weekend talks with an Iranian nuclear envoy.

She said the shift in policy is a signal the administration is serious about diplomacy, but does not mean Washington is ready for open-ended discussions with Iran. Such talks can only occur after Tehran halts activities that could lead to development of atomic weapons.

Rice spoke a day before the State Department's third-ranking diplomat, William Burns, is to attend a meeting in Switzerland with Iran's chief nuclear negotiator Saeed Jalili. The US previously has shunned such gatherings, demanding that Iran first suspend its enrichment and reprocessing of uranium.

"It should be very clear to everyone that the United States has a condition for the beginning of negotiations with Iran, and that condition remains the verifiable suspension of Iran's enrichment and reprocessing activities," she told reporters at the State Department. "That remains the U.S. position and it will continue to be the U.S. position."

Burns will attend a meeting on Saturday with Jalili in Geneva, Switzerland at which Iran is expected to deliver its formal response to a package of incentives being offered it in exchange for the suspension.