The killing of hundreds of stray dogs in a government-organised cull in Karachi, Pakistan, is meeting with anger as images spread through social media, reports rferl.com.

Photos showing scores of dead dogs lined up along roads have led to protests from animal-rights groups and a storm of criticism of city authorities.

Officials quoted by Spain's Cadena SER say the cull is necessary because many of the animals have rabies, a virally borne disease that kills tens of thousands of people worldwide every year.

Pakistani authorities say around 150,000 people in Karachi were bitten by dogs in the past year and some 15-20 percent of them contracted rabies.

Karachi is Pakistan's largest city, with a population of more than 23 million people.

But animal-rights groups say the cull -- in which dogs are usually poisoned -- is inhumane. They argue that rabies can be reduced by vaccinating the canines and the large stray-dog population controlled through sterilization.

Karachi officials say such measures are too costly.

Twitter users uttered alarm at the dog killings, with some arguing that Pakistan's disputed record on human rights suggests there's not much hope for the humane treatment of animals.