Source: U.S. to meet with Iran

WASHINGTON (CNN) - A U.S. envoy will meet with Iran's top nuclear official this weekend - in a break with recent policy - a Bush administration source told CNN Tuesday.

Undersecretary of State William Burns will accompany a European Union delegation to a previously scheduled meeting with Saeed Jalili in Switzerland, the source said.

The delegation will be led by European Union foreign policy chief Javier Solana, said the source, who called the U.S.-Iran meeting "a one-time occurrence."

Burns will not meet separately with Jalili, the source said, but will listen to what Iran has to say and reiterate the U.S. position that Iran must suspend its nuclear enrichment before negotiations can proceed.