VIENNA, Austria — Six world powers agreed Thursday to offer Iran a new choice of rewards if it gives up suspect nuclear activities or punishment if it refuses, a gambit that could either defuse a global confrontation with the Islamic regime or hasten one.

"There are two paths ahead," British Foreign Secretary Margaret Beckett said in announcing agreement among the United States, Britain, France, Germany, Russia and China on a package deal for Iran that carries the threat of United Nations sanctions.

The package would be on the table for a proposed new round of bargaining with Tehran over what the West calls a rogue nuclear program that could produce a bomb. The U.S., in a major policy shift, agreed this week to join those talks under certain conditions. It would be the first major public negotiations between the adversaries in more than a quarter century.

Secretary of State Condoleezza Rice met with the foreign ministers from the European nations that led talks with Iran that stalled last year. Also present were representatives of Russia and China, which have been Tehran's trading partners and might join in any future talks with Iran.

Since Russia and China hold vetoes in the U.N. Security Council, the U.S. needs their cooperation to seek sanctions or other harsh measures by that body.

"We are very satisfied by the results of today's meetings here in Vienna," U.S. Undersecretary of State Nicholas Burns told reporters. "We consider them a step forward in our quest to deny Iran nuclear weapons capability."

A short statement issued by foreign ministers from the six powers and the European Union did not mention economic sanctions — the punishment or deterrent favored by the United States and that Iran has tried hard to avoid.

The powers agreed privately, however, that Iran could face tough U.N. Security Council sanctions if it fails to give up the enrichment of uranium and other disputed nuclear activities, U.S. officials said.

Iran insists its nuclear work is peaceful and aimed at developing a new energy source.

Iran's foreign minister welcomed the idea of direct talks, but rebuffed the U.S. condition that Tehran must put uranium enrichment on hold before talks can begin.