Indian school children travel on an over-loaded rickshaw on their way back home after their school in New Delhi on May 4, 2018.PRAKASH SINGH/AFP/Getty Images

Delhi, India's capital, will become the most populous city in the world, surpassing Tokyo, around 2028, according to the 2018 Revision of World Urbanisation Prospects produced by the Population Division of the UN Department of Economic and Social Affairs (UN DESA), released on May 16.

According to the report, by 2050 two-thirds of people in the world will be living in cities and will be mainly concentrated in three countries - India, China, and Nigeria. These three countries will account for 35 percent of the projected growth of the world's urban population between the time span.

Delhi is likely to become the world's most populous city:

Not only the most populous city, India is expected to make new records as the most populous country by surpassing China.

"By 2020, Tokyo's population is projected to begin to decline, while Delhi is projected to continue growing and to become the most populous city in the world around 2028," the report said, according to Press Trust of India.

In recent years, some cities in the low-fertility countries of Asia and Europe have experienced population decline. Also, two other factors - Economic contraction and natural disasters -have triggered population losses in some cities.

The world is expected to have 43 megacities with more than 10 million inhabitants, mostly in developing regions by 2030. Also, urbanisation will play a huge role as there will be a gradual shift in the residence of the human population from rural to urban areas in Asia and Africa.

Currently, Asia is home to 54 percent of the world's urban population, though levels of urbanization are considered to be low in the region.

Moreover, India reportedly has the largest rural population with 893 million, followed by China with 578 million.

"Many countries will face challenges in meeting the needs of their growing urban populations, including for housing, transportation, energy systems and other infrastructure, as well as for employment and basic services such as education and healthcare. Integrated policies to improve the lives of both urban and rural dwellers are needed, while strengthening the linkages between urban and rural areas, building on their existing economic, social and environmental ties," it said, according to PTI.