South Korea has expressed its displeasure to Tokyo over the comments of a senior Japanese official who suggested that Seoul may have tried to develop nuclear weapons.

The government said Sunday that it had sent Deputy Foreign Minister Lee Soo-hyuck to Tokyo late last month to protest recent remarks by Chief Cabinet Secretary Hiroyuki Hosoda and to reiterate Seoul's commitment to nuclear non-proliferation.

In mid-September, Hosoda called "inappropriate" the two experiments conducted by a small group of South Korean scientists that produced minimal amounts of plutonium and enriched uranium in the 1980s and in 2000.

Hosoda then publicly called for the International Atomic Energy Agency to conduct a thorough investigation into such past experiments.

South Korea has repeatedly said that the experiments were not linked to a weapons program and that it has no plan to make atomic weapons.