Although the six-party talks on North Korea's nuclear programs were expected to start next week, negotiators say it is still not clear when they will resume.
Wu Dawei, China's vice foreign minister and top negotiator in the six-nation talks - on a visit to Japan Thursday - told reporters the date for reopening talks is still under discussion.
Speaking in Japanese, Mr. Wu says he personally would like to see the talks resume on September 2.
Japanese officials also said no date has been set.
The fourth round of negotiations in Beijing recessed August 7, after 13 days. The main sticking point was whether North Korea should have a peaceful nuclear program, or drop its nuclear activities altogether as the United States and others say it should. All sides said they would meet again on the week of August 29.
The past few weeks have seen intense diplomatic activity, including contacts between U.S. and North Korean officials.
U.S. Secretary of State Condoleezza Rice also met this week with South Korean Foreign Minister Ban Ki-moon in Washington, while Japan's envoy to the talks traveled to the U.S. capital to meet with the top American negotiator.
Participants appear eager to avoid a breakdown in the talks, which also include Russia. Until the fourth round opened last month, the process had been stalled for more than a year, with North Korea hesitating to return to negotiations and accusing the United States of taking a hostile attitude.
The issue flared nearly three years ago when the United States said North Korea had admitted having a secret nuclear weapons program in violation of its international agreements. Six-way negotiations began in August of 2003 but the first three rounds failed to produce an agreement.
Officials this time have sounded more optimistic about the outcome than after previous rounds.
Speaking after Secretary Rice's meeting with the South Korean foreign minister Tuesday, a U.S. State Department spokesman said both sides agreed that progress had been made during the last round of talks and that they had seen a "business-like approach" from the North Korean delegation.