Iran's Supreme Leader Ayatollah Ali Khamenei announced in a televised address a ban on the import of coronavirus vaccines from the US and the UK, saying the two countries were "not trustworthy".

"I have already said it to government officials, and now announce it publicly. The import of American and British vaccines is prohibited," Khamenei said in his address on Friday.

"American and British vaccines are not allowed in the country. The US and Britain are not trustworthy," Xinhua news agency quoted the top leader as saying in his address on Friday.

The Supreme Leader also praised the Iranian Covid-19 vaccine now at the human trial stage as a "source of pride" for the country, and voiced hope that other vaccine projects will be developed and improved in the future in the country. After Khamenei's address, the Iranian Red Crescent Society announced that the import of American Pfizer Covid-19 vaccines has been cancelled.

"The import of 150,000 doses of the coronavirus vaccine (developed by) Pfizer Inc from the US to the country by the Iranian Red Crescent Society is cancelled," IRCS spokesman Mohammad Hassan Qosian Moqaddam told the state-run IRNA news agency on Friday night.

"We are ready to cooperate, if necessary, in case (Iran's) Ministry of Health, Treatment and Medical Education puts in a request (for importing vaccines) from eastern countries," Moqaddam added.