Some international public health experts are warning countries not to try Russia's unproven and untested Sputnik 5 COVID-19 vaccine.

They stepped up warnings after Russia's President Vladimir Putin on Tuesday said Russia had registered the world's first coronavirus vaccine. Putin claimed the vaccine "works quite effectively." Sputnik 5 "has passed all the necessary checks," he said without elaborating.

The World Health Organization said vaccines should go through all stages of testing before being licensed. Sputnik 5 has not, it said. The Association of Clinical Trials Organizations said Russia wasn't following the rules.

"The rules for conducting clinical trials are written in blood. They can't be violated," said association executive director Svetlana Zavidova. "This is a Pandora's box and we don't know what will happen to people injected with an unproven vaccine."

Putin said full-scale production would begin in September. Putin claimed one of his daughters had been inoculated twice. The treatment is supposed to provide immunity for up to two years.

"I would like to repeat that it has passed all the necessary tests," Putin said. "The most important thing is to ensure full safety of using the vaccine and its efficiency."

The vaccine is in phase-2 trials, according to experts. There has been no confirmation about critical phase-3 trials which normally involve tens of thousands of volunteers and can last up to six months. There is no published data of either phase-1 or phase-2 trials and the experts said this raised questions about the safety and efficacy of the vaccine.

Scientists in Russia, however, claim they completed phase-2 testing the first week of August. They said they were now conducting phase-3 tests and vaccinating medical workers. Western medical experts said this practice wasn't permitted by U.S. and Europe medical safety regulations.

Russia may start vaccinating doctors as early as this month, Russia's Deputy Prime Minister Tatyana Golikova said. Medical workers, teachers and other risk groups will be the first to be inoculated. The inoculations will be voluntary.

In spite of the international criticisms Putin is promoting the vaccine to other countries such as the Philippines, Brazil and Saudi Arabia. Philippine President Rodrigo Duterte said he wanted to be the first Filipino inoculated with Sputnik 5.

The country's health department, however, has warned against this because the vaccine hasn't completed required clinical trials. Nevertheless, the Duterte administration said the Philippines was ready to join Russia's clinical trials.

Putin is trying to score "a domestic win," Center for Strategic and International Studies senior vice president J. Stephen Morrison said. "It's high risk...this is high risk of backfiring, particularly if there's adverse impact and if they attempt to cover (it) up," Morrison said.

Sputnik 5 is an adenovirus-based vaccine developed by Moscow's Gamaleya Research Institute of Epidemiology and Microbiology and the Russian Direct Investment Fund.

Russia has the world's fourth largest number of confirmed COVID-19 cases. As of Wednesday there were 902,000 confirmed cases and more than 15,000 deaths.