On a crusade against COVID-19: a group of medieval reenactors have heeded a call from the authorities of a Swedish island to help ensure tourists stick to social distancing guidelines.

Clad in full armour and flying banners reading "Together we take responsibility", a total of eight knights will be encouraging the throngs of tourists visiting Gotland this summer to stay chivalrous and mindful.

"We have three messages and those are: keep distance, wash your hands often and stay home if you're feeling unwell," project manager Lennart Borg said, adding that they get a lot of attention, especially when mounted on horses.

The knights are from the reenactment society Torneamentum, which normally puts on jousting tournaments during the summer, now cancelled due to coronavirus restrictions.

Borg told AFP they made their first foray into the field this week, greeting visitors arriving by boat at the harbour.

They will make appearances at beaches and other areas at risk of crowding in the coming weeks.

Located off Sweden's east coast, Gotland's 59,000 inhabitants welcomed close to a million visitors in 2018, and with virus restrictions closing off many foreign destinations, Swedes have been turning up in droves this summer. 

Visby, the island's largest city, already has a flavour of the Middle Ages, and is surrounded by a wall dating back to the 13th century.