A top US envoy to North Korea said talks on delivering food aid to North Korea in exchange for a drawback in its nuclear program made progress, but that details on the deal must still be worked out.

Robert King, special envoy for North Korean human rights issues, said the talks in Beijing on Wednesday and Thursday were "complicated" but that both countries had "made progress." He said he would return to Washington to consult with the government.

The US State Department has said the aid program would provide 240,000 tons of food and would target children, pregnant women and other North Koreans affected by chronic malnutrition. A famine in heavily isolated North Korea in the 1990s killed hundreds of thousands of people, and the country has relied on international aid since then to feed its people.

In return for the food, North Korea would suspend long-range missile and nuclear tests, stop its enrichment of uranium and allow UN officials to monitor the program. North Korea agreed to the deal last week.

The nuclear deal gave new hope for a return to six-nation talks, which also include South Korea, Japan, Russia and China, aimed at putting an end to Pyongyang's nuclear weapons program. The talks have been stalled since North Korea abandoned them in April 2009.

Meanwhile North Korea's chief nuclear negotiator arrived in the United States late Tuesday for three days of unofficial talks. Ri Yong-Ho met with US academics in New York on Wednesday, with South Korean nuclear envoy Lim Sung-Nam also expected to attend.

acb/pfd (AP, AFP, dpa)