VIENNA — Iran has corrected one violation of its landmark nuclear deal with six world powers and is honoring all other major obligations, the U.N. atomic energy agency reported Friday.

The U.N’s International Atomic Energy Agency is responsible for monitoring the agreement Iran signed last year with the United States, Russia, China, Britain, France and Germany that reduces and limits Tehran’s nuclear activities in exchange for sanctions relief.

In February, a month after the deal’s implementation, the agency noted that Iran had produced heavy water beyond its allotted limit of 143.3 tons (130 metric tons.), Friday’s The confidential assessment, obtained by The Associated Press, said Tehran was now below that amount.

Heavy water is a potential proliferation concern because it is used in reactors that produce substantial amounts of plutonium, a potential path to nuclear weapons. Some of the excess was exported in February to the U.S. under an arrangement criticized by U.S. congressional opponents who asserted it facilitated Iranian violations of the deal.

The U.S. House of Representatives voted on Wednesday to bar the U.S. government from purchasing more heavy water from Iran, but a similar amendment died in the Senate earlier in the year. Differences between the two houses have yet to be resolved but any ban is expected to be vetoed by President Barack Obama.

The deal also crimped and set long-term restrictions on uranium enrichment, a process that — like plutonium production — can be turned to making nuclear weapons. Iran was keeping to its commitments on that, the report said.