Dubai ruler Sheikh Mohammed bin Rashid Al-Maktoum said Tuesday he had received an experimental coronavirus vaccine, becoming the latest United Arab Emirates official to take part in the trials.

Two vaccines are undergoing third-phase trials in the UAE, one produced by Chinese drug giant Sinopharm, and Russia's Sputnik-V, named after the Soviet-era satellite.

"While receiving the COVID-19 vaccine today," Sheikh Mohammed captioned a photograph of himself he posted on Twitter with his sleeve rolled up, as a healthcare worker in full protective equipment administered the injection.

"We wish everyone safety and great health, and we are proud of our teams who have worked relentlessly to make the vaccine available in the UAE," he said, without specifying which vaccine he took.

Chinese drug giant Sinopharm began the third phase of trials for a Covid-19 vaccine in the UAE in July and Emirati officials say the results have been positive.

Last month, authorities announced the UAE had also approved clinical trials of Russia's Sputnik V, becoming the first Middle East country to do so.

Sheikh Mohammed is also prime minister of the UAE, a collection of seven emirates which has so far recorded more than 136,000 coronavirus cases, 503 of them fatal.

The foreign minister, Sheikh Abdullah bin Zayed Al-Nahyan, and deputy prime minister Sheikh Saif bin Zayed Al-Nahyan have also taken the experimental vaccine.

In September, Bahrain announced that Crown Prince Salman had taken part in third phase trials of the Sinopharm vaccine.

Dozens of companies, from biotech start-ups to Big Pharma, are racing to develop a safe and effective Covid-19 vaccine.

The World Health Organization has identified 42 "candidate vaccines" at the stage of clinical trials.

Ten of them are at the most advanced "phase three" stage, in which a vaccine's effectiveness is tested on a large scale, generally tens of thousands of people across several continents.