North Korea referred to its missile program Monday in its official media for the first time since it apparently began preparations for a test launch, as a U.S. official confirmed the North has completed fueling a missile that is poised to fire.

Secretary of State Condoleezza Rice leveled a warning that "it would be a very serious matter and indeed a provocative act" if North Korea tested a long-range ballistic missile.

Testing would abrogate several North Korean commitments and "it would be taken with utmost seriousness," Rice said at a news conference.

U.S. intelligence indicates that the long-range missile, believed to be a Taepodong-2, is fully fueled, a U.S. official said in Washington, requesting anonymity because the information comes from sensitive intelligence methods.

That reportedly gives the North a launch window of as much as a month for the missile, its most advanced model that experts say could reach parts of the U.S.

White House spokesman Tony Snow declined specific comment on reports that the fueling is complete.

"North Korea has imposed a moratorium on launching missiles," Snow said aboard Air Force One with U.S. President George W. Bush. "We hope it will continue that moratorium and we hope it also will abide by commitments it made" last year to abandon its nuclear weapons and renounce further development of them, he said.

CountryWatch: North Korea

The U.S. has also talked directly with North Korean representatives in New York, where the country has a mission to the United Nations, Snow said.

He said Bush and other officials have talked on the telephone with more than a dozen heads of state about the indications of a coming launch.

"This is something that the president has been working vigorously," Snow said.

Meanwhile, the North mentioned its missile program on its evening TV news for the first time during the latest crisis, while not saying whether it intended a launch.

The report monitored from Seoul, citing a Russian commentary, said "the U.S. claim that North Korea has a missile that can hit the U.S. is unconfirmed speculation." The report added that the editorial said the North "has the due right to have a missile that can immediately halt the United States' reckless aerial espionage activity."

The North's media is controlled by the state and reflects the country's official position.

The North has repeatedly complained in recent weeks about alleged U.S. spy planes watching its activities. Some of the North Korean reports put the claimed espionage off the country's northeast coast and in the area where foreign officials say preparations for a long-range missile launch are continuing.

Fueling the missile would be a crucial step, some experts said.

"Once the injection of fuel is completed, it is dangerous unless the missile is launched within 24 hours at the longest," said Toshiyuki Shikata, an expert on military affairs and professor at Teikyo University in Tokyo. However, he said the North Koreans could be faking the fuel injection as a bluff.

But Japan's Mainichi newspaper reported Monday that after fueling is finished, the missile has a launch window of about one month, citing unidentified officials in Washington familiar with U.S. and North Korean matters.

There was no launch by Monday evening, and a nighttime test is considered highly unlikely.

Also Monday, the United States, Japan, Australia and New Zealand cautioned the impoverished country that a missile test would bring serious consequences and further isolate the regime.

North Korea fired a missile over northern Japan in 1998, its last such test, and has abided by a self-imposed moratorium since 1999.

"Japan has been urging North Korea to stop the attempt to launch a missile," Prime Minister Junichiro Koizumi said. "We are making efforts to urge North Korea to act rationally and with self-restraint."

"If it does not listen to us and fires a missile, we have to consult with the United States and take stern measures," he added. He refused to specify possible steps, but other officials have mentioned sanctions and an appeal to the U.N. Security Council.

The U.S. ambassador to Japan, Thomas Schieffer, also said sanctions were an option.

"I think sanctions would have to be considered, but I wouldn't want to describe what actions we might take," Schieffer said, according to the U.S. Embassy. He added that a launch would be "worthy" of Security Council discussion and action.

In Seoul, South Korea's ruling party called on Pyongyang not to put its "friend in danger" by testing the missile, as the opposition accused the government of not leaning hard enough on the North to stop the launch.

"It is time for (the North) to make a decisive move toward establishing peace on the Korean Peninsula through cooperation with South Korea," said ruling Uri Party Chairman Kim Geun-tae.

But the South Korean government sought to downplay concerns about a possible missile launch, with domestic media reports in early editions of Tuesday newspapers citing Seoul officials claiming the North may actually be seeking to launch a satellite.

The launch — whether it be of a satellite or a missile — hasn't entered its final countdown, the Hankook Ilbo newspaper said, citing government officials.

In 1998, when North Korea test-fired a Taepodong-1 ballistic missile over northern Japan, the North claimed it was a satellite launch.

The North claims it has nuclear weapons, but isn't believed to have a design that would be small and light enough to top a missile. Pyongyang has stayed away from international nuclear talks since last November, in anger over U.S. financial restrictions against a Macau bank and North Korean companies for alleged illicit activities.