This year's manoeuvres come with Middle East tensions soaring in the face of the Israel-Hamas war that has drawn in Iranian allies around the region, including Yemen's Huthi rebels who have launched a campaign of attacks on commercial shipping in Red Sea and the Gulf of Aden, drawing Western reprisals.

"The naval units of China and Russia entered the territorial waters of our country to take part in the combined maritime exercise," Iran's official IRNA news agency reported.

The manoeuvres, aimed at "jointly maintaining regional maritime security", will begin in the Gulf of Oman on Tuesday night, IRNA said, citing their spokesman, Rear Admiral Mostafa Tajoddini.

The Chinese defence ministry said it had sent a destroyer, a frigate and a supply ship to take part in the joint exercise.

Russian state media reported that a detachment of ships from the country's Pacific Fleet, led by the cruiser Varyag, docked in the Iranian port of Chabahar on Monday ahead of the drills.

"The practical part of the exercise will take place in the waters of the Gulf of Oman in the Arabian Sea," Russian news agencies cited the defence ministry as saying.

"The main purpose of the manoeuvres is to work out the safety of maritime economic activity."

The three countries, which have all had difficult relations with the West in recent years, held joint manoeuvres in the same waters in March last year under the name "Security Bond 2023".