Beijing (AFP) - China, Russia and Iran will hold joint naval drills starting Friday in the Gulf of Oman, Beijing and Tehran said, at a time of heightened tensions since the US withdrew from a landmark nuclear deal with Tehran.

Set to take place from December 27 to 30, the military exercises aim to "deepen exchange and cooperation between the navies of the three countries", Chinese defence ministry spokesman Wu Qian told reporters Thursday.

Wu said the Chinese navy would deploy its Xining guided missile destroyer -- nicknamed the "carrier killer" for its array of anti-ship and land attack cruise missiles -- in the drills.

But he did not give details on how many personnel or ships would take part overall. For Iran, the drill's purpose was to bolster "international commerce security in the region" and "fighting terrorism and piracy," said senior armed forces spokesman Brigadier General Aboldazl Shekarchi.

The exercise would "stabilise security" in the region and benefit the world, state news agency IRNA quoted him as saying on Wednesday. The US reimposed crippling sanctions on Iran in May last year after withdrawing from the international deal aimed at tackling the Islamic Republic's nuclear programme, prompting Tehran to hit back with countermeasures.

Remaining parties to the badly weakened 2015 deal include China, Russia, Britain, France and Germany. China's foreign minister said the exercises were part of "normal military cooperation" between the three countries. In June, US President Donald Trump authorised a military strike after Iran shot down a US drone, only to call off the retaliation at the last moment.