China's special envoy for the nuclear issue on the Korean Peninsula said in Washington that negotiations on the standoff have entered a "substantial period", according to Tuesday's China Daily.

Ning Fukui, Chinese ambassador of nuclear issue on the Korean Peninsula, met with State Department and other US officials as part of a visit to that country late Monday.

Ning did not confirm reports that the new round of six-party talks would take place on June 23.

He stressed that difficulties will increase as more in-depth discussions progress.

Chinese Foreign Ministry spokesman Liu Jianchao said Monday in Beijing that the final date for the third round of talks has still not been set, adding that the different sides are still trying to find a suitable time.

"Various parties have put forward proposals for when the talks should be held. The Chinese side is keeping consultations with the other parties in order to achieve consensus for an early date," he said.

The six nations -- China, Democratic People's Republic of Korea, the United States, Republic of Korea, Russia and Japan held two rounds of talks on the nuclear standoff in Beijing in August and February.

At the first working group meeting held in Beijing last month, negotiators agreed the third round of six-party talks should be held in Beijing before the end of June after one more working-level discussion.

In Washington, Adam Ereli, deputy spokesman of the US Department of State said on Monday that there have been developments since last round of talks and the situation now is "very different" from before.

"We are close to convening a second working group meeting and a third plenary," Ereli said.

Source: Xinhua