In his first public comments on a possible trip to North Korea, U.N. Secretary-General Ban Ki-moon said he was discussing dates for his visit with the isolated state, but that no decision has been reached.

Ban, who is South Korean, said he received "positive signs" from Pyongyang recently following his talks with the North's foreign minister, in comments made to South Korean reporters at the United Nations and carried by YTN TV early on Tuesday.

"We are discussing when would be the good time for me to visit the North, but so far nothing has been decided," he said, adding he is working to make the trip "at the earliest time."

The United Nations had denied news reports about Ban's visit to Pyongyang last week or this week.

If Ban's visit does take place, he is expected to discuss U.N. sanctions against the North and its nuclear weapons programme, analysts have said.

The North is under multiple U.N. Security Council resolutions for its missile and nuclear tests, as well as separate U.S. and EU sanctions.

Ban had earlier this year made plans to visit an industrial park in the North operated jointly by the two Koreas. But Pyongyang withdrew approval for the trip at the last minute without explanation.

Ban served as South Korea's foreign minister from 2004 to 2006, a period of intense multinational negotiations aimed at ending the North's nuclear programme. Those talks led to a 2005 deal that later fell apart.

North and South Korea are technically still at war as their 1950-53 conflict ended in an armistice rather than a peace treaty.