SEOUL, South Korea - North Korea strongly denied Tuesday that it has provided Syria with secret nuclear cooperation, claiming the charge was fabricated to block progress in the North's relations with the United States.

North Korea's Foreign Ministry said the country has upheld a pledge made last October, when it conducted its first-ever nuclear test, that it would be "a responsible nuclear weapons state" and not transfer any nuclear material out of the country.

The North "never makes an empty talk but always tells truth," the ministry said in the statement carried by the official Korean Central News Agency.

The comments were the first by the government in Pyongyang on the issue since suspicions arose after an alleged Israeli air raid earlier this month on unknown Syrian targets.

A senior U.S. nuclear official said Friday that North Koreans were in Syria, and that Syria may have had contacts with "secret suppliers" to obtain nuclear equipment.

Andrew Semmel, acting deputy assistant secretary of state for nuclear nonproliferation policy, did not identify the suppliers, but said North Koreans were in Syria.

In a related editorial Sunday, a state-run newspaper in Syria said "the magnitude of these false accusations might be a prelude to a new aggression against Syria." Al-Thawra said suggestion of such nuclear cooperation was "a flagrant lie."

The North's Foreign Ministry claimed that the suspicions are "nothing but a clumsy plot" fabricated by "dishonest forces" who do not want to see "progress in the six-party talks and in the (North Korea)-U.S. relations."

Six-party talks refer to negotiations aimed at persuading North Korea to give up its nuclear programs. The forum involves China, Japan, the two Koreas, Russia and the U.S.

There has been progress in the nuclear negotiations in recent months, with North Korea shutting down its sole functioning nuclear reactor in July and preparing to disable its nuclear facilities under a February six-party deal. However, a session expected to convene this week has been delayed for unknown reasons.