SEOUL, April 6 (Reuters) - South Korea is considering all options to secure enough coronavirus vaccine supplies, a top vaccine official said on Tuesday in response to questions about possible export curbs on locally made vaccines.

The remarks come as authorities face a backlash for relying on global vaccine-sharing scheme COVAX for a bulk of the country's COVID-19 shots as shipment delays threaten to slow the inoculation programme.

Last week's announcement that South Korea would only receive 432,000 doses instead of 690,000, and that delivery would be delayed to around the third week of April, is the second time that the country's vaccine rollout has been hit by supply delays in the scheme.

When asked whether authorities were considering export curbs on AstraZeneca Plc shots produced by SK Chemicals Co Ltd unit SK bioscience, a COVID-19 vaccination management task force team lead told reporters all options were on the table.

The AstraZeneca vaccine produced by SK bioscience has been shipped to Thailand, Vietnam, Taiwan and global vaccine sharing scheme COVAX which is mainly aimed at ensuring supplies to 64 poor countries.

The Korea Disease Control and Prevention Agency (KDCA) also said it will make an announcement relating to reports that the British regulator is considering a proposal to restrict the use of AstraZeneca vaccine in younger people over concerns about very rare blood clots.

Close to a million first doses of the vaccine had been administered as of Monday, the KDCA said, when it also reported 478 new cases to take the country's total infections to 106,230, with 1,752 deaths. (Reporting by Sangmi Cha; Editing by Kim Coghill & Shri Navaratnam)