Belgium on Monday prepared to fight the spread of the British variant of the coronavirus after outbreak reports in schools and retirement homes of the strain believed to be more infectious.

Carl Decaluwe, the governor of West Flanders, which includes the postcard city of Bruges, said he had ordered a massive wave of testing in several schools.

The measures came after about two-thirds of the residents of a retirement home in the town of Houthulst and one-third of the staff were infected, a statement said.

Three people died, the De Groene Verte home said.

In all about 130 people tested positive with the British strain, the town's mayor told AFP, with the country now seriously considering tougher restrictions on travel in and out of the country.

An outbreak was also reported in a small town near the port city of Antwerp, where two pupils from a primary school in Edegem were infected with the British variant.

"We have promised and guaranteed that we will not make people feel guilty," the town's mayor Koen Metsu told VTM news.

"But it is effectively the case that if everyone had followed the quarantine rules after returning from a trip, we could have avoided this."

Non-essential travel abroad remains strongly discouraged in Belgium.

But the cross-roads country of 11 million people is tucked between France, Germany, Luxembourg and the Netherlands with thousands of people crossing the border every day.

Reports said the government could decide by the end of the week to reduce the maximum length of stay to avoid testing and quarantine from the current 48 hours to 16 hours or shorter.

Belgium has recorded 678,839 cases of the coronavirus and 20,435 deaths, making it the most bereaved country in the world in terms of population.