SEOUL - Peace talks to formally end the Korean War should begin when North Korea declares the full extent of its nuclear arms programme and takes steps to disable it, South Korea's foreign minister said on Thursday.

Officials from China and the United States -- the two signatories, along with North Korea, to the truce that ended the 1950-1953 war -- have said a peace treaty cannot be signed as long as Pyongyang possesses nuclear arms.

"Negotiations for a peace regime should start when the disablement process is under way and its plutonium is disclosed," Foreign Minister Song Min-soon told parliament.

North Korea agreed under a deal in October with the South, the United States, Japan, Russia and China that by the end of the year it would disable its plants that produce weapons-grade plutonium and fully account for its nuclear arms programme.

"The start of the talks must be in parallel with the disablement process," Song said.

Earlier this month, at only the second summit of the divided Koreas, South Korean President Roh Moo-hyun and North Korean leader Kim Jong-il agreed to seek talks with China and the United States for a peace treaty.

Song said a treaty can be reached only when the North scraps its plutonium stockpile.

Washington has said the North, which conducted its first nuclear test a year ago, has produced about 50 kg (110 lb) of weapons-grade plutonium.

"I don't believe we can live in peace with a North Korea that still possess nuclear arms," Song said.