Iran has granted its elite Revolutionary Guards full responsibility for naval operations in the Gulf in the event of a conflict, a new US intelligence report has said.

The Islamic Revolutionary Guard Corps Navy (IRGCN) has several fast attack boats and cruise missiles in place along the Strait of Hormuz and the Gulf, the US Office of Naval Intelligence said in the study made public last week.

The move, which is part of an overall restructuring programme started in 2007, better allows "Iranian naval assets to contribute to and extend Iran's layered defence strategy", the report said.

The Revolutionary Guards has increased its naval capabilities in recent years by incorporating Chinese, North Korean and Italian technology, both military and commercial, it said.

As a result, the Guards now has some of the fastest naval vessels operating in the Gulf, the study said.

Tensions deepening

The report also said that the Revolutionary Guards also wishes to build or acquire "unmanned" naval vessels.

The Islamic Republic of Iran Navy (IRIN) has also placed its own naval assets further into the Gulf of Oman, the report said.

The findings come amid deteriorating relations between Iran and major powers over Tehran's disputed nuclear programme.

Iran said on Sunday that it is aiming to build 10 new uranium enrichment plants as part of an expansion to its nuclear project.

That announcement came two days after the International Atomic Energy Agency (IAEA), the United Nations' nuclear watchdog, rebuked it for secretly carrying out sensitive nuclear work.

Oil supply strategy

The study on Iran's naval capacity cited public statements by Iranian leaders that indicated they would "consider closing or controlling the Strait of Hormuz if provoked, thereby cutting off almost 30 per cent of the world's oil supply".

"Closing the Strait would cause 'tremendous economic damage' to Iran, which would 'probably not undertake a closure lightly'," the study said.

But "disrupting traffic flow or even threatening to do so may be an effective tool for Iran," the report continued.

The IRGCN and IRIN have opened new bases as part of the restructuring programme, the study said. They had previously shared operations in the Gulf, the Caspian Sea, and the Gulf of Oman.

While IRIN has large ships that are able to go extended patrols and missions in open waters, the Revolutionary Guards' naval force has smaller, faster boats geared towards asymmetric warfare, the study said.

"Overall, Iran's development programme has strengthened its naval capabilities, yielding increases in the country's inventory of small boats, mines, anti-ship cruise missiles, torpedoes, and air defence equipment," the study said.