VIENNA (AFP) - Photos of a man aboard a train went viral on Wednesday (Aug 22) due to his unusual travelling companion: a horse.

The man reportedly tried to board two trains in the state of Styer with his horse named Frieda. But train conductors refused to continue the journey with Frieda aboard.

Photos of the young man holding Frieda surrounded by laughing passengers were shared on Twitter and retweeted by state rail company OeBB.

"We hope this will stay a one-off," OeBB spokeswoman Julianne Pamme was quoted by Austrian news agency APA as saying, adding that horses could be dangerous, for example if the train had to break suddenly.

OeBB guidelines stipulate that small, harmless animals in closed and secure containers, as well as dogs on leashes and wearing muzzles can be taken on trains.