South Korea may drop its demand that the North first apologise for sinking one of its warships before long-stalled six-party nuclear disarmament talks can resume, a report said Tuesday.

A willingness by Pyongyang to give up its nuclear ambitions was more important to restart the six-party forum than an apology for the March sinking of the Cheonan, a senior presidential aide told Yonhap news agency.

"With regard to the six-way talks, whether North Korea has the will to denuclearise is the more important condition than (the sinking)," he was quoted as saying.

The comments are being seen as a shift in Seoul's previous policy of linking the two issues, Yonhap said.

Seoul previously opposed reopening six-party talks, saying Pyongyang should first apologise for torpedoing the corvette with the loss of 46 lives, an accusation vehemently denied by the North.

The official, however, stressed that Seoul still regards the ship sinking as "the most important factor" in relations with Pyongyang, Yonhap said.

"Even if we do not set the Cheonan issue as a direct condition, it can be one of the important barometers in judging North Korea's sincerity," he said.

The report comes amid efforts to revive the six-party talks aimed at curbing Pyongyang's nuclear ambitions in exchange for aid.

Pyongyang bolted the forum in April 2009 and conducted its second nuclear test a month later.

The North has indicated a willingness in principle to return to the talks, which are chaired by its ally China and also involve South Korea, Japan, China, the United States and Russia.

But the United States says the North must mend relations with the South and show sincerity about nuclear disarmament before any resumption of the negotiations.

South Korea wants North Korea to disable its nuclear facilities first and allow international monitors back to its nuclear complex.