As South Africa prepares to host foreign ministers from the G20 countries, US Secretary of State Marco Rubio says he would not be attending.

Relations between Pretoria and Washington have been strained under President Donald Trump’s new administration.

Rubio criticised the country’s policies as “anti-American”.

It is the first meeting of foreign ministers from the G20 group of major economies since South Africa took over its presidency in December last year.

A senior research fellow at the Centre for the Advancement of Scholarship at the University of Pretoria, Professor Daniel Bradlow, said the G20 is a voluntary membership grouping. So if an important country like the United States looks like it’s not participating, that’s a negative sign.

Last week, Trump cut aid and assistance to South Africa saying Afrikaners, who are descendants of mainly Dutch colonial settlers, were being targeted by a new law that allows the government to expropriate private land.

Bradlow said major powers such as China would likely look to fill any vacuum left by the United States in the multilateral grouping, but suggested other outcomes were possible too.

The G20 is made up of 19 countries representing some of the world’s largest economies, as well as the EU.

Analysts say Rubio’s absence represents the Trump administration’s indifference to multilateral bodies, but Rubio has also directly rejected South Africa’s priorities for its G20 presidency.

South Africa is the first African nation to hold the G20 presidency and its theme for the grouping this year is “solidarity, equality, sustainability”.