Iran said on Friday it had taken a step to further scale back its commitments to a 2015 nuclear deal, Iran's semi-official ISNA news agency reported.

"Foreign Minister (Mohammad Javad) Zarif, in a letter to EU policy chief (Federica Mogherini) announced that Iran has lifted all limitations on its Research and Development (R&D) activities," ISNA quoted Foreign Ministry spokesman Abbas Mousavi as saying.

Under the nuclear deal between Iran and major powers, Tehran can continue to conduct limited enrichment research and development without accumulating enriched uranium, including work with certain types of advanced centrifuges.

The 2015 deal between Iran and six other countries, reached under former U.S. president Barack Obama, curbed Iran's nuclear work in exchange for the lifting of most sanctions in 2016.

But the United States exited the pact last year and has reimposed sanctions on Iran.