Belgium has confirmed a case of the new, heavily mutated variant of the virus that causes Covid-19, according to one of the country's leading virologists.

The B.1.1.529 variant contains 30 mutations to the spike protein that allows the virus to enter the body, scientist Tulio de Oliveira said Thursday during a briefing held by the South African Department of Health.

The highly contagious delta variant, which the WHO says accounts for 99% of the world's Covid cases, has just two mutations to the receptor binding domain.

The WHO's virus evolution working group will determine whether to list the new strain as a variant of interest or a variant of concern.

The variant of concern label is reserved for Covid mutations that are more contagious, more virulent and more skilled at evading public health measures, vaccines and therapeutics.

The emerging variant arrives in Europe amid an already devastating Covid surge linked to the delta strain.