Seoul, South Korea - Unused rooftops provide a perfect environment for breeding bees, residents of South Korea's capital Seoul have discovered.

Over the past year, the number of bee hives in the region has almost doubled from 180 to 300.

"Urban bee-keeping lets you realise that people don't exist alone in an urban space, but have to coexist," says Park Jin, the founder of Urban Bees Seoul.

"It shows you the importance of honeybees. Breeding them in a city helps pollination, helping to improve the ecology as well."

Bees, he says, are a welcome addition to the environment.

In a polluted, industrialised city that lacks greenery, Park Jin's bees have to work particularly hard for their nectar.

READ MORE: Saving the bee

Choi Kwang-Bin, a member of the Seoul Metropolitan Government, says environmental issues are high on the agenda.

"Seoul is surrounded by mountains. But daily life, green space within the reach of your hands is more important than greenery you can look at," he said.

"Constantly providing more green space within living areas is one of Seoul’s core policies."

It is hoped that greenery will attract more bees. That would help to pollinate more plants as environmentalists foresee a dramatic decline in the global bee population.

While beekeeping cannot reverse the trend, it can raise awareness.

In the largest metropolis of South Korea, people have signed up to study the art of keeping bees in the city, which could cast a greener light over a grey cityscape.