At least 26 residents living in a Belgian care home have died from COVID-19 following a visit from a volunteer dressed as Santa Claus who has also since tested positive for the virus.

On top of the 26 fatalities, 85 other residents have tested positive for the virus, along with 40 staff since the event on December 5.

A health official told the AFP news agency that it is not yet certain where the outbreak came from, and it is unknown whether it was the visitor who brought the virus to the Hemelrijck home in Mol, northern Belgium.

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In Belgium, 'Sinterklaas', the country's equivalent to Santa Claus, traditionally brings gifts to Belgians every December 6, but the COVID-19 pandemic marred most of 2020's celebrations.

The outbreak was detected several days after the visit, with virologist Marc Van Ranst saying on Twitter that most of the infections came from the same source.  

Regional health spokesman Joris Moonens said that no inquiry had been launched because no formal complaint was raised, adding that there was no suggestion the volunteer knew he was infected when he visited the home.

A crisis manager has been sent to Hemelrijck to help staff, residents and relatives cope "in this difficult period," Moonens added.

Belgium has one of the world's highest per-capita COVID-19 death rates, with more than half of those killed by the virus retirement home residents.

The Guardian reported that Armonea, the company that runs the residential care home, said its staff had taken the appropriate measures to keep residents safe.