A North Korean diplomat publicly appealed to Japan on Wednesday to urge the United States to lift sanctions on Pyongyang, saying the North won't return to nuclear disarmament talks until that happens.

"We are ready to return to talks under one condition, and that is that the United States lift its sanctions," said Song Il Ho, the chief envoy to talks with Japan on forming diplomatic relations between Tokyo and Pyongyang.

"The United States won't hear this from us. But if Japan tells the United States, if a friend tells a friend, they might listen," Song said at a news conference. "Please, Japan, go and tell the United States."

The United States has sanctioned North Korean companies accused of proliferating weapons of mass destruction and a Macau bank accused of helping Pyongyang to launder money.

North Korea promised in September to give up nuclear development in exchange for aid and a security guarantee. But it has refused to return to talks while U.S. sanctions are in place.

Song was speaking after Japanese and North Korean envoys wrapped up five days of talks on possible diplomatic relations without reaching any agreements. They said they would meet again but didn't set a date.