Inmates are to be restricted to their cells in a Belgian prison after more than half of a facility's population tested positive for Covid-19.

Quarantine measures have been introduced at Namur prison following the rapid spread of coronavirus among its 132 prisoners.

Inmates will not be allowed walks or showers, but will have a hot meal and hygiene products delivered daily.

One inmate is in hospital with the virus, according to officials.

As well as half of prison inmates, about 60 of the facility's 115 staff members have also tested positive for the virus.

Kathleen De Vijve, a spokeswoman for the prison administration, described the situation as "very serious".

All visits have been suspended to the facility and several family members of prisoners gathered outside the prison on Saturday to protest the decision, public broadcaster Rtbf reported.

Belgium has been under restrictions now for four months with a night curfew and all hospitality closed, but schools remain open.

Despite this, infections have started to rise again with officials confirming on Friday that a more contagious virus variant originally found in the UK has now become dominant.

"Last week, we estimate that 53 percent of infections were caused by the UK variant, against 38 percent a week earlier," virologist and government spokesman Steven Van Gucht said.

Prof Van Gucht said the rise in infections has put the country roughly a month back from where it was.

Belgium's prime minister, Alexander De Croo, said at a Friday news conference that he had hoped to announce a relaxation of lockdown measures, but the situation remains "extremely delicate" and at "a difficult moment".

"We were on a high plateau, but the figures are now rising again," he said.

"It forces us to be particularly careful...When there is a storm you cannot set out. With these figures, we cannot ease."

He said the government would take a "time-out week" before making further decisions.

Belgium has seen more than 766,000 confirmed cases and 22,000 deaths since the outbreak began.