WASHINGTON (AP) _ North Korea delivered rocket fuel this week to the launch site where U.S. officials believe it is preparing to test-fire a long-range missile in defiance of American warnings, a senior U.S. official said Friday.

The fuel deliveries were an additional indication that North Korea may test as early as this month, although no missile has yet been detected at the site, the official said, speaking on condition of anonymity.

U.S. intelligence also has detected activity by North Korean radars at the launch facility this week, including those radars expected to be used in tracking a ballistic missile in flight, the official said.

The issue is particularly sensitive because the United States and South Korea have insisted that North Korea abandon its ballistic missile development as a condition of normalizing relations. The North and South have been in a technical state of war since an armistice ended the Korean War in 1953. The United States has no formal diplomatic relations with North Korea but is moving in that direction.

The Pentagon on June 30 first publicly acknowledged that U.S. intelligence had detected ``some preparations'' for a launch in coming weeks or months, but it has declined to be more specific.

The Clinton administration has repeatedly said that a missile test launch would have ``serious consequences'' for North Korea but has not threatened military retaliation. The U.S. view is that a long-range missile capability for North Korea would destabilize the region. South Korea, for example, would come under increased domestic political pressure to develop missiles that can strike deeper into North Korea. In the 1970s Seoul agreed _ under U.S. pressure _ to limit the range of its missiles.

Adding to the worry in Washington is a belief that North Korea has or is pursuing nuclear weapons that could be delivered by missile.

The Washington Times reported Friday that U.S. intelligence agencies believe several hundred North Korean military advisers are helping the government of President Laurent Kabila in the Congo's civil war and may be paid in uranium ore from the same mine that was the source of ore for the first U.S. nuclear weapons in the 1940s.

North Korea has denied it is developing nuclear weapons.

The official Korean Central News Agency said in a report Friday that Washington is using the missile test issue as a pretext to attack North Korea and to justify its ``madcap arms buildup in South Korea.''

``We warn the United States once again that whether we launch a satellite or missile, it belongs to our sovereign right,'' the report said. ``If the United States projects a `military countermeasure' at any cost, (North Korea) will retaliate against it with a stronger countermeasure.''

North Korea's first launch of a Taepo Dong missile, last Aug. 31, took the U.S. government by surprise, triggered outrage in Japan and put in doubt the future of U.S. relations with the communist North. The two-stage missile, with an estimated range of 1,000 miles, flew over Japan and landed in the Pacific.

The incident triggered a Clinton administration reassessment of its policy toward North Korea and an offer, conveyed to North Korean officials by former Defense Secretary William Perry in May, to lift the decades-old U.S. economic embargo against the North in exchange for an agreement to end missile development and other concessions.

The United States believes North Korea is developing longer-range missiles, including the Taepo Dong 2, possibly capable of reaching U.S. territory. In addition to the direct threat such a missile could pose, the Clinton administration is concerned that North Korea would sell such technology to other nations hostile to America.