The aid package – which would be the largest shipment since 2000 – was agreed to early on Tuesday after Pyongyang announced it would end its boycott of nuclear disarmament talks.
But the agreement is separate from incentives the South has offered the communist North to attract it back to the international arms negotiations it has refused to attend for more than a year.
US Secretary of State Condoleezza Rice said on Tuesday the nuclear talks will fail unless North Korea is committed to abandoning its nuclear weapons.
"What we really need is a strategic decision on the part of the North that they are indeed ready to give up their nuclear weapons programme," Rice told reporters after the meeting with Japanese Foreign Minister Nobutaka Machimura in Tokyo. "Without that, these talks cannot be successful."
Return to talks
Pyongyang said over the weekend it would return to the nuclear talks the week of 25 July, after a meeting with the top US nuclear envoy in Beijing.
Seoul has prepared a significant aid proposal for the North if it returns to the arms negotiations, which were last held in June 2004, but has refused to release details of the offer.
Local media reported the proposal would be revealed at a meeting later on Tuesday of South Korea's National Security Council to be chaired by President Roh Moo-hyun.
Rice said the North must be ready
to give up its nuclear programme
A spokesman for Roh's office, speaking on condition of anonymity, declined to directly confirm the reports but said there was movement within the presidential Blue House to publicise the plan.
Opposition parties have called for transparency in dealings with the North - especially after revelations in recent years of secret payments to Pyongyang ahead of a 2000 summit between leaders of the two Koreas that paved the way to reconciliation.
Rice was scheduled to arrive on Tuesday evening in Seoul and was expected to discuss the revived nuclear arms talks at a Wednesday meeting with Roh.
Later this week, the chief nuclear negotiators from Japan, South Korea and the United States will meet in Seoul to coordinate strategy for the next round of arms talks, the South Korean Foreign Ministry said.
Chinese goodwill trip
Also on Tuesday, a Chinese special envoy, State Councillor Tang Jiaxuan, arrived in North Korea, the North's official Korean Central News Agency reported.
Tang is on a goodwill trip as President Hu Jintao's personal representative.
At the close of inter-Korean economic talks early on Tuesday, the two sides agreed that the South would give the North raw materials to help it produce clothes, shoes and soap for internal consumption by its impoverished population.
The two Koreas are to conduct a
pilot run of their railway link soon
In return, the South will be given investment rights in North Korean mining operations for zinc, magnesite and coal, the sides said in a joint statement.
The North and South also agreed to conduct a pilot run in October of reconnected railway links across their heavily armed border and hold an opening ceremony for restored roads.
The two Koreas also will open an economic cooperation consultation office at a joint industrial zone just north of their border.