KNOKKE-HEIST, Belgium (Reuters) - Belgium has set up a new system to track mobile phones in order to limit crowding of seaside resorts and beaches that formally open for the summer season on Saturday.

Health authorities across Europe are concerned at the prospect of masses flocking to local beaches and risking the spread of the coronavirus, such as at the English resort of Bournemouth on Thursday.

Belgium’s coastal towns are not seeking to bar tourists from coming, but do want them to use common sense, such as rerouting to a less busy spot or choosing to shop later.

The 10 districts along the coast will detect mobile phones on beaches and the nearby dikes and seafronts and display the live information on a website, with codes from dark green for calm to orange for very busy.

A further 130 sensors in the towns will indicate to people the busy spots they may wish to avoid. The website also hopes to give an indication of how busy the resorts are likely to be in the coming days.

The chic town of Knokke-Heist has also put in place beach markings to indicate 3 square metre (32 square feet) boxes.

“We have implemented what we call ‘beach bubbles’, where one family or friends can be together in a safe way and to visualize the distance that they should be from one another,” Anthony Wittesaele, town councillor for tourism, told Reuters.

Swimming in the sea off Belgium is banned until the on-season, when lifeguards are patrolling. The COVID-19 pandemic has delayed the start of the season from May to this Saturday. It runs until mid-September.