Britain on Thursday said it was concerned by a newly identified coronavirus variant spreading in South Africa that might make vaccines less effective and imperil efforts to fight the pandemic.

The UK Health Security Agency (UKHSA) said the variant, which is called B.1.1.529, has a spike protein that was dramatically different to the one in the original coronavirus that Covid-19 vaccines are based on.

"This is the most significant variant we have encountered to date and urgent research is underway to learn more about...