"AstraZeneca is disappointed to announce a shortfall in planned COVID-19 vaccine shipments to EU despite working tirelessly to accelerate supply," it said in a statement.
The Sinovac shipment arrived with huge fanfare at Bangkok's airport, with a Chinese embassy official vowing that the vaccine export showed the "strengthened relations between China and Thailand".
Denmark, Norway and Iceland on Thursday temporarily suspended the use of AstraZeneca's Covid-19 vaccine over concerns about patients developing post-jab blood clots.
Denmark however suspended the use of all of its AstraZeneca supply, as did Iceland and Norway in subsequent announcements on Thursday citing similar concerns.
The country of more than 80 million has lost more than 61,000 lives out of over 1.7 million cases of Covid-19 infection, according to health ministry figures.
This was brought in after British-Swedish drugs giant AstraZeneca failed to meet promised delivery schedules to EU members while honouring its British contract.