UN Secretary-General António Guterres has urged world leaders gathered in Bishkek to "stop the madness" and end the world's wars.

Speaking to Euronews in the Kyrgyz capital on the margins of the Shanghai Cooperation Organisation (SCO) summit on Tuesday, the UN chief said the meeting was a rare chance to put the case directly to the people who could act on it.

"A very important message is to say, it is time to stop this madness. It is time for peace. And some of the key actors of these processes are here," Guterres said.

"What worries us more is the fact that we have conflicts that seem never-ending. It is true in relation to Russia and Ukraine. It is true in relation to the Middle East, both from Gaza to the Iran and United States confrontation," he added.

On Iran, Guterres said strikes had resumed, and called for both sides to return to negotiations, which he said had come close to succeeding.