Australia said on Wednesday the European Union asked it to withdraw export permit applications for exports of AstraZeneca's Covid-19 vaccine, and its denial that it blocked shipments were simply "semantics".
The dispute emphasises the challenge facing European nations to vaccinate their populations and the impact on any vaccine export restrictions on countries that had pre-ordered doses.
Here's a timeline of how the shipment of 3.1 million doses of AstraZeneca's vaccine from Europe to Australia has stalled.
Australia orders 3.8 million doses of Europe-manufactured Covid-19 vaccine being trialled by Oxford University and AstraZeneca Plc for early 2021 delivery that is to underpin the early stages of Australia's inoculation programme, now running behind schedule.
Australia bankrolls biopharma CSL Ltd to make another 30 million doses of AstraZeneca vaccine domestically, later increased to 50 million.
Australia also orders 10 million doses of Covid-19 vaccine being developed by Pfizer and BioNTech.
European Union grants conditional approval for AstraZeneca vaccine.
Australia grants Pfizer/BioNTech vaccine approval. Prime Minister Scott Morrison says he plans to have 4 million of the country's 25 million population vaccinated by the end of March.
EU introduces export controls over vaccine, citing supply shortage.
AstraZeneca says only 1.2 million offshore-manufactured vaccine doses can be delivered to Australia by end-March, due to export controls.
First Pfizer vaccines arrive in the country; first inoculations take place.
Australian health authorities approve AstraZeneca vaccine.
Australia receives first shipment of the AstraZeneca vaccine from Europe, with 300,000 doses.
AstraZeneca applies to the EU for export licence to ship another 500,000 doses, which are being made in Italy, to Australia, according to Morrison.
EU tells AstraZeneca to re-submit application for just 250,000 doses. Australia agrees to a temporary reduction, Morrison says.
EU blocks the shipment of 250,000 doses - that had already been negotiated down from 500,000 - to Australia, says Morrison.
Australia writes to EU requesting 1 million doses of its original 3.8 million order to help with "humanitarian crisis" in neighbouring Papua New Guinea.
Australia reaches end-March milestone with about 600,000 vaccine doses administered, compared to 4 million target.
Morrison says end-March target was missed because 3.1 million AstraZeneca vaccine doses ordered from Europe and due by end-march were not delivered.
EU denies blocking vaccines to Australia other than one shipment of 250,000 AstraZeneca doses from Italy.
Morrison says the EU has not responded to Australia's request for 1 million AstraZeneca vaccines for Papua New Guinea and invites EU to send outstanding 3.1 million doses to confirm it has not blocked exports.
Locally-manufactured AstraZeneca vaccines are being administered. A shipment of 400,000 offshore-produced AstraZeneca doses are due by the end of April.