Japan may slap further sanctions on North Korea if it fails to comply with a United Nations resolution prompted by its surprise missile tests earlier this month, the government's top spokesman said Friday.

It is "extremely regrettable" that North Korea has not agreed to return to continuing multilateral talks aimed at getting Pyongyang to abandon its development of nuclear weapons and advanced missile technology, chief Cabinet spokesman Shinzo Abe told reporters.

CountryWatch: North Korea

"We feel it is necessary for North Korea to implement the United Nations Security Council resolution and return immediately to the six-party talks without setting preconditions," he said. The six-party talks include the Koreas, Japan, the United States, Russia and China.

Abe added that Tokyo would watch the North's response to continuing discussions in Kuala Lumpur, Malaysia among countries at this week's Association of Southeast Asian Nations security forum and decide whether further sanctions are called for. The forum in Malaysia ended Friday.

"We need to decide after considering North Korea's response at the Asia Regional Forum and whether it will make a sincere response toward the various problems," he said.

Foreign Minister Taro Aso told U.S. Secretary of State Condoleezza Rice that Japan is considering additional measures to sanction North Korea during a meeting in Malaysia, the Foreign Ministry said.

Later in the day, North Korea's foreign minister, Paek Nam Sun, told delegates to the ASEAN Regional Forum, or ARF, that his country might pull out of the security conference attended by 25 countries and the European Union if it condemned North Korean actions, according to diplomats.

Prime Minister Junichiro Koizumi called for calm.

"It's one thing to threaten and it's another to actually pull out. We should not overreact," he said.

Japan is reportedly considering revising foreign exchange and trade laws as part of sanctions imposed on North Korea in response to the recent missile tests. The revisions are expected to require about 300 Japan-based companies who trade with North Korea to disclose the destinations of any exports of about 40 materials that could aid the North's missile program.

Also on Friday, Japan's Agriculture Ministry said it will begin asking retailers and wholesalers to verify the origin of seven products imported from North Korea that often carry false labels.

The inspection will start nationwide on Aug. 1 and include clams and expensive "matsutake" mushrooms, according to ministry official Shinji Kobayashi. Violators could be fined, or given a prison sentence, Kobayashi said.

North Korea fired seven missiles in early July, including at least one believed capable of reaching the U.S. mainland. International condemnation prompted the Security Council to adopt a resolution sanctioning North Korea and banning member states from missile-related dealings with the communist country.

The North has since rejected the resolution, warning of further repercussions.