The two Koreas on Wednesday extended their first direct talks in 10 months for an extra day as South Korea (search) tried to convince the communist North to return to the nuclear bargaining table.

The talks came amid heightened concerns over North Korea's (search) nuclear ambitions. Pyongyang said last week it removed fuel rods from a reactor — a step toward extracting weapons-grade plutonium.

There has been speculation that North Korea might be preparing to conduct a nuclear test, which U.S. officials have said would lead to unspecified actions; Japan (search) says it would seek U.N. sanctions.

The talks had been scheduled to end Tuesday afternoon. But the delegations remained at the North Korean border village of Kaesong overnight, then held a half-hour meeting Wednesday morning and announced they would hold more talks on Thursday.

The nuclear issue was the hangup. The reclusive, impoverished North — which often uses brinksmanship to wring aid and concessions from the West, had sought additional fertilizer and food aid, but South Korea clearly linked that to Pyongyang rejoining six-nation talks on its worrisome nuclear weapons program.

"We have made it clear that we cannot accept North Korea's nuclear weapons, and if the principal of denuclearization on the Korean Peninsula is not followed, reconciliation and cooperation between the South and the North would be impossible," Vice Unification Minister Rhee Bong-jo, head of the South's delegation, told reporters.

He said South Korea "has fully delivered its position" through various channels.

Rhee earlier said the North had listened without comment to his push for Pyongyang to rejoin the nuclear negotiations, which it has boycotted since a third round ended last June. On Wednesday, he only would say they were still listening.

The North has shunned direct talks with the South over its nuclear program, but has become dependent on food aid to ease widespread famine, and the spring planting season is looming.

Hopes for a breakthrough had faded Tuesday, when the South reported no progress on the nuclear issue and the two delegations — scheduled for a working lunch before ending their second and final day of talks — suddenly announced they would eat separately.

But the North didn't walk out in a huff as they often have in the past when the South has tried to broach the nuclear issue.

On Monday, South Korea promised a major new "proposal" if the reclusive communist North returns to stalled disarmament talks involving the United States, China, Japan, Russia and the two Koreas.

No details on the proposal were given, but South Korean media speculated that Seoul would offer massive aid to its impoverished neighbor. North Korea said on Monday that it wanted to talk about food aid and fertilizer; Rhee responded that the size of such aid needs further consultations.

U.S. State Department spokesman Richard Boucher offered support for the South's initiative, but said Washington believes such aid for the North "shouldn't be conditioned or negotiated as part of the six-party talks."

China appealed to the United States and North Korea on Tuesday to hold direct contacts in order to restart the six-nation talks.

"China hopes these two countries can have contacts so they can build mutual trust and understanding," said China's Foreign Ministry spokesman Kong Quan.

The United States says any contacts it has with North Korea must be within the six-nation negotiations. The two governments have never had official relations.

North Korea claimed in February that it has nuclear weapons and said it would indefinitely boycott arms talks until Washington drops its "hostile" policy. It said last week it would strengthen its nuclear arsenal, and that it had removed spent fuel rods from a reactor — a possible step toward making nuclear bombs.

U.S. officials reported last week that spy satellites spotted construction of a tunnel and a reviewing stand in North Korea — possible indications of a coming nuclear test.

South Korean officials have dismissed such reports as lacking firm evidence.