People aged 65 and older will outnumber under-15s in Europe by 2024, the World Health Organization said Wednesday, warning of new social, economic and health challenges.

Europe is decades ahead of the global shift, which is expected to take place 60 years later, around 2064, according to projections by the Our World in Data institute.

"By 2024, it is estimated that the population of individuals aged over 65 years will outnumber those under the age of 15 in the WHO European Region," the WHO said in a statement.

"This trend means new social, economic and health challenges, which demand a focus on healthy ageing to mitigate the impact of an ageing population," it added.

The WHO's European region covers 53 countries, including several in Central Asia.

Across Europe, longer life expectancy is often synonymous with declining health.

To mitigate the impact of population ageing, the WHO called for measures to "enable older people to preserve and improve their physical and mental health, independence, social well-being and quality of life."

Among the recommendations were policies that increase sporting and cultural activities for older people.

It also said older adults could improve their health by eating a balanced diet, doing a minimum of 150 minutes per week of moderate physical activity, as well as activities that maintain balance, mobility and reduce loss of muscle mass and bone density.

"Engaging in even higher levels of physical activity can reduce the risk of all-cause mortality by 35 percent," the WHO said.