Seoul's comments on Wednesday came as the two Koreas extended senior-level talks over the North's nuclear programme after a two-day meeting ended in a stalemate over whether Pyongyang would return to six-way negotiations.
The talks, which were scheduled to end on Tuesday, continued overnight into early Wednesday, but made no breakthrough. The meetings were due to resume on Thursday.
South Korean Foreign Minister Ban Ki-Moon said on Wednesday that his country's proposal was based on an existing one, but "more acceptable" to participants. He did not elaborate.
"Based on the proposal put forward at the third round of six-way talks in June last year, we will discuss details on what contents to be included in it (the new offer) with related states," Ban told a weekly briefing.
"Our government believes it is very important to have six-way talks resumed at this time when the North Korean nuclear issue faces a critical juncture, and to make substantial progress if the talks reopen," Ban said.
North Korea has boycotted the six-way nuclear disarmament talks since the third round in June last year, citing a "hostile" US policy.