The World Health Organization (WHO) said on Friday there was no reason to stop using AstraZeneca's COVID-19 vaccine after several European countries suspended the rollout over blood clot fears.

"Yes, we should continue using the AstraZeneca vaccine," WHO spokeswoman Margaret Harris told reporters, adding: "There is no indication to not use it."

The spokesperson's remarks came after a string of countries suspended the use of AstraZeneca's COVID-19 vaccine following reports of the formation of blood clots in some people who had been vaccinated.

Austria on Sunday stopped using doses from one batch after a 49-year-old female nurse died 10 days after vaccination because of "severe blood coagulation problems".

Denmark suspended the shots for two weeks after a 60-year-old woman, who was given an AstraZeneca shot from the same batch used in Austria, formed a blood clot and died, Danish health authorities said.

Two Italians are reported to have died after receiving the vaccine, and an unnamed source told Reuters news agency that their deaths are what prompted the temporary suspension.

Four other countries - Estonia, Lithuania, Luxembourg and Latvia - have stopped inoculations from the batch while investigations continue, European medicine regulator, European Medicines Agency (EMA) said.

Thailand has delayed its roll-out of the AstraZeneca COVID-19 vaccine, a health official said Friday. The kingdom was scheduled to start the Oxford/AstraZeneca vaccine roll-out on the same day, with Prime Minister Prayuth Chan-ocha expected to get the first jab.

EMA said the the vaccine's benefits outweighed its risks and could continue to be administered, stating "there is currently no indication that vaccination has caused these conditions, which are not listed as side effects with this vaccine."

AstraZeneca said the drug's safety had been studied extensively in clinical trials. "Regulators have clear and stringent efficacy and safety standards for the approval of any new medicine," a spokesperson said.

(With input from agencies)