Vienna, Austria ? U.N. nuclear agency tests have concluded that traces of highly enriched uranium on centrifuge parts were from imported equipment – rather than from any enrichment activities by Iran, a senior Western diplomat said Saturday.

The findings support Iran’s claims that the material entered the country together with centrifuge parts provided by Pakistan. The diplomat who confirmed the results spoke on condition of anonymity because of the sensitivity of the case.

“The source of contamination was not related to Iran,” said Iran Foreign Ministry spokesman Hamid Reza Asefi. “We are sure the source is not internal.”

The United States has alleged the material was produced by Tehran and the particles were evidence that Iran was experimenting with producing highly enriched uranium, which is only used in nuclear weapons.

The traces were found on centrifuges in the city of Natanz in 2003 and raised concerns about the motives behind Iran’s nuclear activities. Iran has insisted it is only interested in processing low-enriched uranium to generate electricity.

The International Atomic Energy Agency has been testing centrifuge parts provided by Pakistan as well as uranium found on centrifuges bought by Iran on the nuclear black market. Pakistan provided the components earlier this year to compare the traces and assess Iran’s claims of innocence.

Both the agency and the White House declined to comment on the findings.

On Friday, Iran’s supreme ruler said his country does not intend to build nuclear weapons, but it will continue to enrich uranium because it does not want to be dependent on others..

Ayatollah Ali Khamenei also said Western claims Iran is secretly trying to make weapons are “a propaganda trick to deceive their own public opinion.”

Meanwhile, Tehran rejected allegations by the dissident National Council of Resistance of Iran that the country had manufactured thousands of centrifuges.