The U.N. agency monitoring the Iran-six power nuclear pact is reporting no clear violations of the agreement meant to crimp the ability of Tehran to make atomic arms.

But in one area of potential concern, Thursday’s report said Iran had begun manufacturing rotor tubes for centrifuges, machines used to enrich uranium.

Iran is allowed to make such parts but there are limitations.

For the 5,060 centrifuges now producing limited amounts of fuel-grade enriched uranium, Tehran must use spare parts stripped from old machines. Parts for more advanced centrifuges would fall under even tighter regulations.

The confidential report obtained by The Associated Press said “related technical discussions” on the issue are ongoing.

Depending on its enrichment level, uranium has a variety of uses ranging from reactor fuel to fissile warhead cores.

(AP)