The announcement of the manoeuvres coincides with Iranian President Ebrahim Raisi's official visit to Moscow, where he said Tehran has "no limits for expanding ties with Russia".

The drills also come during talks in Vienna aimed at salvaging a 2015 nuclear deal between Iran and world powers, including Russia and China. That agreement had offered Tehran relief from crippling international sanctions in return for deep curbs to its nuclear programme.

Then-US president Donald Trump unilaterally withdrew his country from the pact in 2018 and reimposed sanctions, leading Tehran to begin reneging on its commitments.

The spokesman for the exercises, Admiral Mustafa Tajeddini, told state television that they would include "the participation of 11 naval units from the armed forces of Iran, three units from the Revolutionary Guards' navy, three units from Russia and two units from China".

He added that they would take place over an area of 17,000 square kilometres (almost 6,600 square miles) in the northern Indian Ocean.

Tajeddini said they aim to "enhance capabilities and combat readiness, strengthen military ties between the Iranian, Russian and Chinese navies, ensure common security and counter maritime terrorism".

The three countries held similar drills in the Gulf of Oman and the Indian Ocean in late 2019, when tensions had risen between Iran and its US-allied Arab neighbours in the Gulf.