Dhaka, the capital and megacity of Bangladesh, has been ranked one of the least safe cities in the world, whereas, Tokyo once again topped the list of The Economist's Safe Cities Index 2017.

Dhaka and Karachi in South Asia, Manila, Ho Chi Minh City and Jakarta in South-east Asia and Cairo and Tehran in the Middle East and Africa, are among the 10 cities placed at the bottom in the overall ranking of the index.

The Safe Cities Index 2017 is a report, published last Thursday, from The Economist Intelligence Unit sponsored by NEC. 

The report is based on the second iteration of the index, which ranks 60 cities across 49 indicators covering digital security, health security, infrastructure security and personal security.

The top three cities in the index are unchanged from 2015, with Tokyo, Singapore and Osaka ranked first, second and third and still separated by mere tenths of a point.

Dhaka ranked the 58th with an overall point of 47.37, according to the index.

"This is a reflection of a number of factors, but the main reason is that among the cities in the index, it experiences by far the most frequent and most severe terrorist attacks. Jakarta, which ranked last in 2015, is 57th this

year, pulled from the bottom by the addition of Karachi and other cities like Yangon and Dhaka," the study said.

On digital security, Dhaka along with other low-income cities -- Ho Chi Minh City, Yangon and Manila -- often lack technology skills and competing challenges such as tackling infectious diseases and poverty can push cyber security lower on the list of priorities, the study reveals. 

Three of the top ten in this category are in Asia (Tokyo, Singapore

and Hong Kong) and six (Chicago, Toronto, San Francisco, Los Angeles, New York and Dallas) in North America.

On health security, Dhaka's position is second from the last. As among the poorer cities, it is struggling to deliver adequate health services. Of the bottom ten cities in this category, nine are either low-income cities (Mumbai, Yangon, Dhaka and Karachi) or low-middle income cities (Johannesburg, Quito, Caracas, Jakarta and Cairo), it said.

Of the top ten performing cities in the health security category, only two (Tokyo and Zurich) are high-income cities; and some high-income cities perform poorly, such as Doha, which ranks 45th.

On infrastructure security, Dhaka is placed at the bottom ten in this category along with other lower-income cities -- Mumbai, Delhi, Manila, Yangon and Karachi.

All the cities in the top ten in this category of the index (Singapore, Madrid, Barcelona, Stockholm, Wellington, Amsterdam, Hong Kong, Melbourne, Sydney and Zurich) are either high or uppermiddle income cities.

And finally, on personal security category Dhaka ranked 43rd and Karachi got the last place among the bottom 10 countries.

The top ten cities in this category of the index are Singapore, Wellington, Osaka, Tokyo, Toronto, Taipei, Hong Kong, Melbourne, Stockholm and Amsterdam. 

"While cities generate economic activity, the security challenges they face expand and intensify as their populations rise," Chris Clague, who edited the report 'Safe Cities Index 2017: Security in a Rapidly Urbanising World', says.