"We did not make the progress that I think we would have liked, and we believe that the North Koreans need to come in a more constructive spirit," Rice said.

"But it does not mean there were not very productive discussions that took place during that round," she said.

For his part, Song urged the DPRK to make "a positive and realistic response" to the proposals made to Pyongyang during the talks held in December in Beijing.

Meanwhile, a State Department spokesman said on Friday that the six-party talks aimed at solving the nuclear issue of DPRK is expected to resume this month.

During the round of six-party talks in September 2005, DPRK signed a statement agreeing to give up its nuclear weapons program in exchange for economic aid and security guarantees from the United States and other countries. However, DPRK refused to return to the talks as a result of US financial sanctions.

Under pressure, DPRK returned to the talks in December held in Beijing. However, the talks failed to make progress.