Thai zoo keepers wore superhero costumes while spraying super-strength liquid silver solution on animal enclosures ‘to defeat’ Covid-19.

Chiang Mai zoo officials wore Super-Man and Captain America suits while the other staff were dressed in personal protective gear as they sanitised the area on January 18.

They used Silver Nano 9, a spray made from 99.99 per cent pure silver minerals instead of alcohol as it is more affordable.

The sprays were developed by experts from the Mae Cho University to provide a cheaper alternative for businesses that have large areas to spray regularly.

Aside from having fewer production costs, makers of the Silver Nano 9 liquid claim it has an effectivity of up to 14 days while regular alcohol-based disinfectants should be used daily as they can only stay for up to 24 hours.

Wuthichai Muangman, director of the zoo, said: ‘We are wearing superhero costumes to show everyone that we can defeat Covid-19.

‘This also gives confidence to visitors that our sprays can kill the virus. With this Silver Nano 9, our protection against the virus is longer.’

Thailand has recorded 12,594 Covid-19 infections and 70 deaths. A second wave started in mid-December when hundreds of Burmese migrant workers at a seafood market tested positive. Cases have since spread to more than 45 provinces and lead to lockdowns and mass closures of businesses in some regions.