Hong Kong Special Administrative Region (HKSAR) said on Friday it will delay shipments of AstraZeneca's COVID-19 vaccine this year amid mounting concerns over possible links between the shot and very rare cases of blood clots.

HKSAR had ordered 7.5 million doses from the British-Swedish company, which were scheduled to arrive in the second half of 2021.

Health Secretary Sophia Chan said the global financial center had a sufficient supply of vaccines, with a total of 15 million doses of Germany's BioNTech and China's Sinovac - the only two vaccines available in the region.

"Even if we have signed a pre-purchase agreement with AstraZeneca, we believe that AstraZeneca vaccines will not need to be supplied to Hong Kong this year, so as not to cause a waste when the vaccine is still in short supply globally," Chan said.

The regional government was considering buying a new type of vaccine that may offer better protection, she added.

More than 700,000 COVID-19 vaccine doses have been administered to the region's 7.5 million population so far.

Earlier on Friday, Australian Prime Minister Scott Morrison said his country doubled its order of the Pfizer Inc. COVID-19 vaccine. Until late Thursday, Australia based its vaccination program largely on AstraZeneca.

The Philippines and South Korea have suspended the use of AstraZeneca shots for people under age 60.

Italy on Wednesday joined France, the Netherlands, Germany and others in recommending a minimum age for recipients of AstraZeneca's shot, and Britain said people under 30 should get an alternative.

European and British regulators said on Wednesday they had found possible links between AstraZeneca's vaccine and very rare cases of blood clots, but reaffirmed the vaccine's importance in protecting people against COVID-19.

Hong Kong has registered more than 11,560 coronavirus cases, with 207 deaths.