Posters defending Bulgarian stray dogs have surfaced in London underground stations.

The initiator of the campaign is the Four Paws animal welfare foundation, according to reports of Bulgarian Sega daily based on information posted on social networks.

"Bulgaria's strays are in crisis. Around 100 000 dogs live on the country's streets, in constant threat of death. Sadly, many people see them as vermin and, although it's illegal, kill them to reduce their numbers. But you can help. Four Paws has a humane solution to reduce the population – neutering. It costs just GBP 3 for the anesthetic to neuter one dog. Four Paws is their only hope. Please help," the poster reads.

Four Paws invite people to contribute by sending a short text message to a short code.

The problem with the stray dogs in Sofia came into the spotlight over the demise of Professor Botio Tachkov, a renowned economist, who died Sunday after being brutally attacked by a pack of stray dogs.

The accident triggered public outrage, as the city has been struggling to cope with its increasing stray dog population for years now.