Russian President Vladimir Putin has said a locally developed vaccine for Covid-19 has been given regulatory approval after less than two months of testing on humans.

Mr Putin said the vaccine had passed all the required checks, adding that his daughter had already been given it.

Officials have said they have plans to start a mass vaccination in October.

Experts have raised concerns about the speed of Russia's work, suggesting that researchers might be cutting corners.

Amid fears that safety could have been compromised, the World Health Organization (WHO) urged Russia last week to follow international guidelines for producing a vaccine against Covid-19.

The Russian vaccine is not among the WHO's list of six vaccines that have reached phase three clinical trials, which involve more widespread testing in humans.

Calling it a world first, President Putin said the vaccine, developed by Moscow's Gamaleya Institute, offered "sustainable immunity" against the coronavirus.

Health Minister Mikhail Murashko said the vaccine had "proven to be highly effective and safe", hailing it as a big step towards "humankind's victory" over Covid-19.

Last week, the Russian government announced it was preparing to begin mass vaccinations after saying it had carried out successful trials of the vaccine.

More than 100 vaccines around the world are in early development, with some of those being tested on people in clinical trials.

Despite rapid progress, most experts think a vaccine will not become widely available until mid-2021.

"Sometimes individual researchers claim they have found something, which is of course, as such, great news," WHO spokesman Christian Lindmeier told reporters on 4 August.

"But between finding or having a clue of maybe having a vaccine that works, and having gone through all the stages, is a big difference."