White House expects N.Korea summit to happen despite Pyongyang's silence

* North Korea state media mum on summits with U.S., South Korea

* Tillerson says U.S. expects to hear from North Korea directly

* S.Korea officials visiting China, Japan and Russia this week

* Chinese President Xi Jinping urges patience

* U.N. urges leaders to seize "critical moment" (Adds Tillerson comment on "neutral" site, paragraph 8)

By Steve Holland and Christine Kim

WASHINGTON/SEOUL, March 12 (Reuters) - The White House said on Monday it fully expected an unprecedented meeting between U.S. President Donald Trump and North Korean leader Kim Jong Un to take place, if North Korea stuck to its promises, even though Pyongyang has yet to comment publicly on the possibility of a summit.

A South Korean delegation that visited North Korea last week said North Korean leader Kim Jong Un expressed a wish to meet Trump and South Korea's president to discuss denuclearization. North Korean media have reported the South Korean visit, but no details of the talks.

Asked if the North Korean silence meant there was a chance the meeting between Trump and Kim would not take place, White House spokeswoman Sarah Sanders said: “We fully expect that it will.

"The offer was made and we’ve accepted. North Korea made several promises and we hope that they would stick to those promises and if so the meeting will go on as planned," she told a regular briefing.

Earlier, South Korea said North Korea's silence on summits with both the United States and South Korea was probably because of caution in preparing for the meetings, while U.S. Secretary of State Rex Tillerson said Washington expected to hear directly from Pyongyang.

"We have not seen nor received an official response from the North Korean regime regarding the North Korea-U.S. summit," said Baik Tae-hyun, spokesman for South Korea's Unification ministry.

"I feel they're approaching this matter with caution and they need time to organise their stance."

Tillerson said several steps would be necessary to agree on the location and scope of the talks, adding later that a "neutral" site would be needed.

"It's very early stages. We've not heard anything directly back from North Korea but we expect to hear something directly from them," he said during a visit to Nigeria.

In an unexpected move last week, Trump agreed to hold a first-ever meeting with Kim, which South Korea said would take place by the end of May after a North-South summit in April.

News of possible talks has been a dramatic turnaround from fears of war over North Korea's development of nuclear-tipped missiles capable of hitting the United States.