SEOUL, South Korea -- South Korea's president says he and President Barack Obama have agreed to offer North Korea a "grand bargain" aimed at ending the North's nuclear program.

Speaking at a joint news conference with Obama, President Lee Myung-bak said the deal would be similar to his proposal for a package of political and economic incentives in exchange for the one-step, irreversible dismantling of North Korea's nuclear program.

Lee's grand bargain proposal stems from concerns that North Korea would continue to backtrack on promises after winning concessions in negotiations.

Obama said his envoy on North Korea, Ambassador Stephen Bosworth, will travel to the country early next month for the first bilateral talks with the communist regime since he took office.

North Korea has been pushing for bilateral talks with Washington to discuss the standoff over Pyongyang's nuclear program. The U.S. has agreed to the talks but has stressed they must lead to the resumption of six-nation disarmament negotiations.

North Korea conducted a nuclear test and test-fired a series of missiles earlier this year.

On Iran, Obama said the U.S. and its allies are working on ways to send a "clear message" to Tehran on its nuclear program.

Iran's foreign minister said Wednesday that Iran will not ship its low-enriched uranium out of the country for processing, again rejecting a U.N. plan aimed at thwarting any attempt by Iran to make nuclear weapons.

Obama said that over the next several weeks, the U.S. and its allies will work on developing a package of potential sanctions designed to pressure Iran to accept what Obama said is a fair offer.