The appeal came after one-day security talks in Tokyo between defense and foreign affairs officials from the two countries.

"As to North Korean issues including the nuclear matter, we agreed that it is necessary for North Korea to take the initial phase steps as soon as possible," the Japanese Foreign Ministry said in a statement, referring to the actions mapped out in a February joint agreement between North Korea and five other countries to denuclearize the North.

"We also confirmed that the two countries will continue to closely work together," said the statement, released after the closed-door meeting. The talks were attended by Kenichiro Sasae, Tokyo's chief envoy to international disarmament talks, and Kim Jae-shin, the head of the South Korean Foreign Affairs Ministry's Asia bureau.

The officials did not make public comment. The meeting came amid divisions between the two neighbors over future prospects for disarming the North.

The South is optimistic that a dispute over North Korean bank funds will be resolved soon, while Japan is frustrated with the slow pace of Pyongyang's disarmament, and is reportedly considering additional sanctions against the North.

One hold up in progress on the nuclear talks has been difficulty in finding a foreign bank willing to accept US$25 million (€18.4 million) in North Korean funds from a Macau bank accused of aiding the North in money laundering and counterfeiting.

North Korea, which has so far refused to start dismantling its nuclear program, asked last week that an American bank receive the funds, according to an official familiar with the issue.

South Korean Foreign Minister Song Min-soon on Wednesday that solutions under consideration were "realistic, effective and acceptable," without elaborating. Japanese Foreign Minister Taro Aso, however, said Tokyo had worries that Pyongyang was dragging its feet.

Japan's largest daily newspaper, the Yomiuri, reported Thursday that Tokyo was considering additional sanctions against North Korea if Pyongyang fails to keep its promise of taking steps toward denuclearization.

Tokyo may impose a total ban on exports to North Korea, and may also ban all the foreign ships that have stopped over in the North before coming to Japan, the paper said.

Currently, Japan bans exporting materials related to weapons of mass destruction to the North, as well as luxury goods, and bars all North Korean ships from entering Japan.

A Japanese foreign Ministry official denied the Yomiuri report, saying no specific sanction measures are currently being considered under the scenario in the report. The official spoke on condition of anonymity, citing protocol.

North Korea missed an April deadline to close the Yongbyon nuclear reactor under a February agreement at the six-country talks on the North's nuclear program, but has said its commitment to the deal remains unchanged.

The talks involve the two Koreas, Japan, China, Russia and the United States.

Japan and South Korea, both U.S. allies who host American forces, also exchanged opinions about security policies of both countries and agreed to hold a similar meeting soon, the statement said.