Rice made her remarks at a joint press conference with Egyptian Foreign Minister Ahmed Abul Gheit after a group meeting with foreign ministers from Egypt, Jordan plus the six nations of the Gulf Cooperation Council -- Saudi Arabia, Bahrain, United Arab Emirates, Oman, Qatar and Kuwait.

It would be a "very provocative act" by the DPRK, yet they have not done it yet, she told the press conference, which was dominated by questions over the disputed Iranian nuclear program and DPRK's nuclear test.

A nuclear test by the DPRK will create a big difference in the Korean peninsula situation, she said, adding that it was not just an issue for the America, but a "quite serious issue" for the entire neighborhood.

As for a U.S. possible military operation against the DPRK if it conduct a nuclear test, Rice said the U.S. would need to assess the options.

Earlier in the day, U.S. State Department spokesman Sean McCormack said in a statement that a nuclear test by the DPRK would pose an "unacceptable" threat to peace and stability in Asia and the world.

A nuclear test would "severely undermine our confidence in the DPRK's commitment to six party talks and would pose an unacceptable threat to peace and stability in Asia and the world," said McCormack in the statement.

"A provocative action of this nature would only further isolate the DPRK," McCormack said.

"The U.S. will continue to work with its allies and partners to discourage such a reckless action and will respond appropriately," he added.

McCormack was also in the Egyptian capital accompanying Rice, who arrived here earlier in the day on a two-day visit to Egypt as part of a regional tour, which has already taken her to Saudi Arabia.

Rice and McCormack's remarks came after the DPRK announced earlier in the day that it would conduct a nuclear test in the future as a war deterrent against the hostile the U.S. policy. In a statement issued by the DPRK's Foreign Ministry, it said that the country "will in the future conduct a nuclear test under conditions where safety is firmly guaranteed," according to the official Korean Central News Agency.

However, the statement did not give a specific date or location for the upcoming test.

The six-party talks, which involves China, the DPRK, the United States, South Korea, Russia and Japan, have been stalled since the first phase of the fifth round of talks ended last November.

The DPRK insists on the abolishment of U.S. sanctions against it as a precondition for its return to the negotiation table.