North and South Korea have concluded high-level talks with pledges of future cooperation, but no concrete progress on major issues such as the North's abduction of South Korean civilians or its nuclear weapons programs.

Four days of talks in Pyongyang closed Monday without an agreement from North Korea to return to talks aimed at ending its nuclear weapons programs.

In a statement at the end of the talks, North Korea and South Korea pledge to cooperation on peacefully resolving the nuclear issue.

Pyongyang says it will not resume nuclear talks with South Korea, China, Japan, Russia and the United States until Washington ends financial sanctions on North Korean businesses suspected of counterfeiting and other crimes.

The U.S. says the issues are separate and has urged North Korea to return to the talks and come back into compliance with its pledges to not have nuclear weapons.

The South Koreans received a similarly vague pledge of cooperation on resolving what the statement calls "people whose fate remains unknown" since the 1950's Korean War.

The wording refers to South Koreans believed to be held against their will in the North.

South Korean authorities estimate the North holds more than 500 prisoners taken during the war. In addition, Seoul estimates Pyongyang has abducted more than 400 South Koreans, many of whom are still believed to be alive.

Choi Woo-yong, president of South Korea's biggest abductee advocacy group says the statement is a small step forward.

Choi say she is encouraged by the pledges of practical steps. She says she expects the two Koreas to agree on concrete steps toward identifying and repatriating abductees when they meet again next month in Busan, South Korea.

Monday's statement does not address the high-profile case of South Korean Kim Young-nam, believed to be still alive in the North. Japanese authorities say tests indicate Kim was probably the husband of Japanese abductee Megumi Yokota.

North Korean leader Kim Jong Il admitted in 2002 that his country's spies abducted Yokota and 12 other Japanese citizens in the late 1970s and early 80s. Pyongyang officials say Yokota is dead.

Japanese media reported Monday that police there have obtained arrest warrants for two former North Korean agents believed to have been involved in abductions. One man is now thought to be living in the South.

South Korea says it will consider a request North Korea made during the talks for half a million tons of rice and 300 thousand tons of fertilizer to ease its severe food shortages. South Korea has shipped more than two million tons of fertilizer and hundreds of thousands of tons of food to the impoverished North since 1999.