North Korean media mentioned a visit by a delegation from the South last week, but no coverage has been seen of Kim Jong Un's invitation to meet U.S. President Donald Trump or the South Korean president to discuss the future of Pyongyang's nuclear weapons programme.
"We have not seen nor received an official response from the North Korean regime regarding the North Korea-U.S. summit," Baik Tae-hyun, the spokesman of the South's Ministry of Unification, told a regular news conference.
"I feel they're approaching this matter with caution and they need time to organise their stance."
The South Korean officials who took Kim's invitation to Washington are visiting China and Japan this week to update their neighbours on the talks.
South Korea's National Security Office chief, Chung Eui-yong, who led the delegation, heads to Russia on Tuesday after meeting Chinese President Xi Jinping, the Blue House said.
In Beijing on Monday, Xi told Chung the Korean peninsula faces an important opportunity for talks to ease the situation.
"At the same time, all sides must exercise patience and be attentive, and show political wisdom, to appropriately face and dispel any problems and interference to resuming the talks process," state media cited Xi as saying.
China looks forward to smooth talks between the two Koreas and between the United States and North Korea and substantive progress in the denuclearisation process and normalisation of ties, Xi added.
Chung expressed thanks for China's role at a meeting earlier with China's top diplomat, State Councillor Yang Jiechi.
Trump agreed to meet Kim Jong Un by the end of May and the two Koreas will hold a summit by the end of April. A location has not been decided for the North Korea-U.S. summit, while Kim and Moon will meet at the truce village of Panmunjom straddling the border of the two Koreas.
North and South Korea agreed to hold working talks to hammer out the details of the inter-Korean summit, but have not officially spoken since the South's delegation returned last week, Baik said.
In Geneva, the U.N. investigator on North Korea said any progress in the nuclear and security dialogue at the planned summits must be accompanied by talks on human rights violations, including political prison camps.
"Let me urge the DPRK to consolidate this rapprochement with a parallel opening to human rights review," said Tomas Ojea Quintana, U.N. special rapporteur on human rights in the Democratic People's Republic of Korea (DPRK).
"My main message today is that any advancement on the security dialogue should be accompanied by a parallel expansion on the human rights dialogue," he told the world body's Human Rights Council.
The North's official news agency has been lauding the two sides' efforts to thaw relations, but state media have continued to warn the United States and Japan against war-mongering.
Rhetoric in the North's state media has been tame, however, compared to threats last year that Pyongyang would fire missiles into the vicinity of the U.S. territory of Guam if provoked.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)