Portugal detected 13 cases of the Omicron coronavirus variant on Monday, all involving players and staff of top-division soccer club Belenenses SAD, one of whose players recently returned from South Africa, health authority DGS said.

The diagnoses were made after the Lisbon club played a Portuguese first-division match against Benfica on Saturday that started with only nine Belenenses players on the pitch because of a COVID-19 outbreak.

Only seven players returned to the field after halftime, and the match was abandoned two minutes into the second half with Benfica leading 7-0.