The candidate has yet to complete its final trials and scientists have expressed fears that Moscow may be putting national prestige before health.
It comes as Germany’s leading infectious disease institute said a vaccine could be available as early as autumn, but warned it may take longer to control the pandemic.
"It seems our foreign colleagues are sensing the specific competitive advantages of the Russian drug and are trying to express opinions that are completely groundless," Russian health minister Mikhail Murashko said on Wednesday.
Officials have said that the vaccine, called "Sputnik V" in homage to the Soviet Union satellite, will be administered to people on a voluntary basis in the final trial.
Mass roll-out across is expected to start in October.
Scientists from the UK, Germany and the US are among those questioning the motives behind approving the vaccine before testing is complete.
The Moscow-based Association of Clinical Trials Organisations (ACTO), a trade body representing the world's top drugmakers in Russia, has also urged the country’s health ministry to postpone approval until the final trial is complete.
"It's the ambition, the desire to be first in a field in which, unfortunately, Russia cannot vie for a top spot," ACTO executive director Svetlana Zavidova said.
"Our task is now to warn the population because we so far don't understand how they (the authorities) are going to carry out mass vaccination."
Final trials, normally carried out on thousands of participants, are considered essential in determining safety and efficacy.
Only about 10 per cent of clinical trials are successful.
The Philippines and Kazakhstan have expressed interest in the vaccine, while the World Health Organisation says it has not received enough information to evaluate it.
Vladimir Putin, who said the vaccine had already been administered to one of his daughters without any problems, and a string of other officials have insisted it is safe.
Germany’s Robert Koch Institute said in a statement that it would be “dangerous” to trust any vaccine developed this year, even if it is approved.
“Preliminary projections make the availability of one or several vaccines seem possible by autumn 2020,” the infectious disease centre said in a statement.
However, it cautioned: “It would be dangerous at this point to trust that a vaccination from autumn 2020 can control the pandemic.”
The impact of any vaccine could be limited because of viral mutations or because first products to market may offer only short-term immunity, the institute added.
German biotech firm BioNTech, which is working with US pharma giant Pfizer on a vaccine, has said it aims to file for emergency approval as early as October if ongoing trials succeed.