A boom in city beekeeping in Britain may not be the best thing to have happened to the country's honeybee population, exerts say.

Dense bee populations in areas where there are few flowering plants to feed them adds pressure to the troubled species, especially as honeybee declines have been linked to a lack of suitable habitat, the experts say.

Planting more flowers rather than adding new hives would be a better way for nature lovers to help the bees, researchers at the University of Sussex say.

Rooftop hives in London have become increasingly popular but scientists warn inexperienced beekeepers could be risking the health of their bees.

"If there are too many colonies in an area, then the food supply will be insufficient," Sussex researcher Francis Ratnieks said. "This will mean that colonies do not thrive, and may also affect other species that also visit flowers."

The researchers urged planting wildflowers in open city spaces to relieve the pressure on city bees.

"Marjoram, borage, lavender, catmint, and Bowle's Mauve all attract bees, are easy to grow, and are beautiful as well," Ratnieks told the BBC.