BEIJING — North Korea may have used a launch pad in Iran to test a new missile capable of hitting American bases in the Pacific island of Guam, according to reports from Japan and South Korea.

The missile, named after the Musudan testing range in North Korea, was recently shown off to the public at a vast military parade in the capital, Pyongyang, according to the reports. South Korean and American intelligence reports suggest that the weapon may then have been tested in Iran, with which North Korea is known to have military links.

The Musudan missile had not been previously recorded. North Korea has a known capacity to build short- and medium-range missiles, including the Taepodong-1 which it fired over Japan in 1998 to the alarm of Tokyo and its allies in Washington.

However, it has had less success with developing long-range missiles. It has been working for several years on a Taepodong-2, which would be targeted at America’s western seaboard. But a test launch carried out last July ended in failure, with the missile landing in the sea not far from the border between North Korean and Russia.

The new missile is said have been identified by American military satellite pictures of the rally held in April to commemorate the 75th anniversary of the founding of the North Korean army. The weapon is thought to be based on Soviet technology.

The Japanese Defense Ministry confirmed yesterday that the new missile might be able to travel 3,000 miles at middle altitude. “We acknowledge that such a new type of missile is being developed by North Korea in addition to the existing missiles,” an official said.

The South Korean news agency, Yonhap, quoted a source in Washington as saying: “We did obtain intelligence tips that the missile was test-fired in Iran. I understand that the intelligence communities of relevant countries are tracking down the information.”

If the test did take place in Iran, it could have been a quid pro quo for North Korea’s alleged agreement to share with Tehran the results of the nuclear test it carried out last October.

Both countries benefited from the “nuclear supermarket” run by Abdul Qadeer Khan when he was head of Pakistan’s nuclear program. Until he was placed under house arrest in Islamabad three years ago, Mr. Khan sold component parts and crucial expertise to both Iran and North Korea. The Pyongyang regime returned the favor by transferring missile technology to Pakistan. But Iran does not have anything similar to offer North Korea. It is unlikely to be able to offer missile or nuclear know-how.

The use of a test site is one of its few options for payment. The only other would be for Iran to offer North Korea cash — and with the second largest oil reserves in the world, it has plenty of funds available.