SEOUL: A new nuclear treaty with the United States governing South Korea's commercial nuclear activities during the next 20 years went into effect Wednesday, the South Korean government said.

The treaty, which replaces a previous accord reached in 1972, opens the possibility of South Korea gaining the ability to enrich uranium to produce non-weapons-grade nuclear fuel depending on future negotiations with the United States.

The new treaty took effect after South Korea's foreign minister and the US ambassador exchanged documents in Seoul, the Foreign Ministry said in a statement.

The countries agreed to the revised treaty in April after spending several years arguing over whether South Korea should have the right to enrich and reprocess US-origin nuclear fuel for commercial purposes.

The revised deal does not give South Korea that right, but provides for establishment of a high-level committee to further discuss the issue, which Seoul officials described as a step toward potential consent.

South Korea has been seeking the ability to enrich uranium to produce nuclear fuel, which it says will help reduce import costs and support its exports of nuclear reactors. It also wants to be able to reprocess spent fuel to reduce its growing amounts of nuclear waste.

The US restricts such activities because the same technologies can be used to produce weapons-grade nuclear fuel, and because of fears that supporting South Korea's enrichment ambitions might send the wrong signal to North Korea, which is developing its own nuclear weapons program.

The revised deal also gives more leeway to South Korea for research activities and data collection related to spent fuel.