The 45-year-old said on Saturday she had tested positive and that she had probably caught the virus from a relative rather than at work.

Her spokesman did not immediately respond to requests for comment, but Alexander De Croo, who took over as prime minister at the start of October, said on Twitter he hoped she would recover swiftly.

"No one is immune to this virus. All together, we will defeat COVID-19," he wrote.

Wilmes led the country as prime minister through the first six months of the pandemic, then switched jobs after her minority administration was replaced by a majority coalition this month.

Infections and hospital admissions are continuing to rise in Belgium, which has among the world's highest rate of fatalities per capita from COVID-19.

Health Minister Frank Vandenbroucke warned on Sunday of a possible "tsunami" ahead, with the country starting to lose control of the virus.

Belgium is second only to the Czech Republic in Europe in terms of infections per capita in the past two weeks.

The country of 11 million people reported 9693 new infections per day in the week to October 18, a 75 per cent increase from the week before.

An average of 319 people were admitted to hospital every day.

So far, 10,539 people have died.

The government is set to meet on Friday to discuss the pandemic.

Leading virologist Marc Van Ranst said on Thursday the country needed to go into a short, full lockdown to avoid a long partial lockdown that would exhaust everyone and hit the economy.

Australian Associated Press