The drills -- which state TV showed featured fast boats, shore-to-sea missiles and surface-to-surface missiles -- are part of a string of exercises, dubbed Eqtedar or "might" in Farsi, that began in early January and are set to continue until mid-March.

Iran's army and the Islamic Revolutionary Guard Corps (IRGC) have been taking part.

"The message of this exercise is peace and friendship for neighbouring countries and that we are capable of creating the security of this strategically sensitive region ourselves," the IRGC's naval commander Rear Admiral Alireza Tangsiri told state TV.

Three strategic islands -- Greater Tunb, Lesser Tunb and Abu Musa -- are located in the Gulf near the Strait of Hormuz, through which a fifth of world oil output passes.

They have been a source of contention between the United Arab Emirates and Iran for decades.

Tangsiri added that the exercises are held to "confront any invasion by extra-regional forces and if the enemy wants to threaten the interests of our heroic nation in this region, it will definitely receive a very strong response".

In previous drills, the armed forces unveiled an advanced reconnaissance ship as well as conducted exercises on safeguarding Iran's nuclear facilities in the western and central parts of the country.

The military activities are taking place with Iran's nuclear programme under close watch as US President Donald Trump returns to the White House.

In his first term, Trump pulled the United States out of a 2015 nuclear deal with Tehran and ordered the killing of veteran Guards commander Qasem Soleimani in a US drone strike in neighbouring Iraq.