North Korea has rejected an offer of talks from the South as “insincere”, in a rare meeting of high-level officials.
South Korean authorities told reporters that its foreign minister Kang Kyung-wha spoke to her North Korean counterpart Ri Yong Ho on Sunday on the sidelines of a forum in Manila.
Tensions have escalated on the Korean peninsula in recent months amid repeated missile tests by the North.
The UN Security Council voted on Saturday to impose fresh sanctions.
South Korea proposed talks with the North last month, but Pyongyang has yet to officially respond.
South Korean media reported that Ms Kang and Mr Ri shook hands in a brief and unarranged meeting at an official dinner event held by the Association of Southeast Asian Nations (Asean).
A South Korean foreign ministry official confirmed the meeting to reporters. However China, which is Pyongyang’s closest ally, has disputed this account.
Foreign minister Wang Yi told journalists on Monday: “My feeling is that the North did not entirely reject the positive proposals raised by the South.”
He added that China also supported the South’s initiatives. All three countries’ ministers are attending the Asean forum in Manila.
The US Secretary of State Rex Tillerson is also at the forum, where he spoke about North Korea.
He told journalists that the unanimous vote by the UN Security Council to impose new sanctions was “quite clear in terms of being no daylight among the international community” on their desire for North Korea to stop its tests.
He also made a note of Russia and China’s participation in the vote.
The two countries have previously differed with others on how to handle Pyongyang, but in recent months have joined in calls for North Korea to stop its missile tests while also urging the US and South Korea to halt military drills.
On Monday, US President Donald Trump spoke to his South Korean counterpart Moon Jae-in over the phone about relations on the Korean peninsula.
They agreed that North Korea “poses a grave and growing direct threat” and the two leaders were committed to fully implement the latest round of UN sanctions, the White House said in a statement.
North Korea has is yet to officially respond to the new sanctions. A senior official told South Korea’s Yonhap news agency: “We will make our stance clear when things are determined.”
But ruling party newspaper Rodong Sinmun earlier said nuclear action or sanctions taken by Washington would lead to an “unimaginable sea of fire” engulfing the US.