Updated

Negotiations over Iran's nuclear program are entering their final phase with just 48 hours until a deadline for Tehran and six world powers to reach a deal.

With the June 30 deadline looming, U.S. Secretary of State John Kerry was meeting Sunday in Vienna with Iranian Foreign Minister Mohammad Javad Zarif, their third encounter since Saturday. Other foreign ministers are expected to join.

The goal of the talks involving Iran and the U.S., Britain, China, France, Germany and Russia is a deal that would crimp Tehran's capacity to make nuclear weapons in exchange for sanctions relief.

On Saturday, diplomats said Iran was considering a U.S.-backed plan for it to send enriched uranium to another country for sale as reactor fuel, a step that would resolve one of several outstanding issues.