South Korean President Lee Myung-bak has called on North Korea's new leader Kim Jong-un to seize the opportunity and return to dialogue.
He said he was prepared to offer help to revive the North's shattered economy if it suspends nuclear activities.
"We have left the window of opportunity open," Mr Lee said in a New Year address broadcast from South Korea's presidential Blue House.
"If North Korea comes forward with sincerity, we will be able to open a new era for the Korean peninsula together.
"As soon as North Korea suspends nuclear activities in progress, six party talks should be able to resume.''
The six party talks - involving the two Koreas, the United States, Japan, Russia and China - have been stalled since 2008 when the North walked away from an aid-for-disarmament deal.
Two days after a state funeral for Kim Jong-il, North Korea vowed to continue a hardline policy.
In a New Year message issued in its state newspapers that normally sets out policy for the year, the North made no mention of its nuclear programmes which had been the key source of regional security worry during Kim Jong-il's reign.
Under Kim Jong-il's leadership, the reclusive state twice tested nuclear devices, as well as a variety of missiles.
