The highly contagious Delta variant of the coronavirus is surging through Asia this week, with record numbers of infections in Australia and South Korea, prompting some countries to tighten curbs and others to hasten vaccination.

The variant, first detected in India in December last year, has spread to about 100 countries and the World Health Organisation warned recently that it could soon become the dominant form of the virus. It is also driving a spike in cases in Japan, casting a pall over this month's Olympic Games.

On Friday, Australia's New South Wales state, its most populous, reported the biggest daily rise in new cases so far this year. Total cases in the state in the latest outbreak have topped 200, a majority caused by the Delta variant.

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