"For South Korea, President Moon wants to improve inter-Korean ties but that's hard without progress in US-North Korea talks", he told AFP.
The statement didn't give an exact date but said the inter-Korean summit would be held "within September in Pyongyang".
At the leaders' first meeting in April, at the border village of Panmunjom, Mr Moon agreed to visit Pyongyang this autumn.
Seoul has been examining nine cases of potential imports of North Korean coal, which would breach a resolution passed last August by the U.N. Security Council to choke off funding for Pyongyang's nuclear and ballistic missile programs.
A string of North Korean weapons tests past year, during which Pyongyang claimed to have completed its nuclear arsenal, had many in Asia anxious that Washington and Pyongyang were on the brink of war.
North Korea is thought to have a growing arsenal of nuclear bombs and long-range missiles and to be closing in on the ability to reliably target anywhere on the USA mainland.
Moon was part of the South Korean delegation which travelled to Pyongyang for the second inter-Korean summit held in October 2007.More news: Afghanistan says Taliban attack on Ghazni repulsed
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The meeting comes amid a growing standoff on North Korean denuclearization that has followed Kim's summit with President Donald Trump in June in Singapore.
The ministerial talks began on the North's side of the truce village of Panmunjom on Monday.
Cho did not say if North Korea had raised the case of the restaurant workers on Monday, merely saying it had not brought up new issues.
The decision comes as nuclear negotiations between North Korea and the United States are deadlocked.
The summit meeting, if held, would mark the third of its kind between the two Korean leaders following their face-to-face meetings in April and May.
North Korean officials have toured China to discuss economic development and speculators are snapping up property along their common border.
Afterwards the North's chief delegate Ri Son Gwon said the meeting had gone well and the date for the summit was "ready", but they had not announced it as "reporting would be more fun when reporters are curious".
But Harry Harris, the United States ambassador to South Korea, said on Monday it was "too early" for such a declaration, Yonhap reported.