Despite a surge in foreign tourists, Tokyo stayed fourth out of 40 major global cities in the annual Global Power City Index (GPCI) ranking unveiled Wednesday, trailing London, New York and Paris.

Compiled annually by the Mori Memorial Foundation's Institute for Urban Strategies, GPCI assesses each city's power to "attract creative individuals and enterprises" and "mobilize their assets for economic and social development," based on criteria such as economy, research, cultural interaction, livability, environment and accessibility.

This year's outcome marks eight straight years Tokyo was ranked fourth since the launch of the ranking in 2008. Although it has made improvements in certain areas, the city is still struggling to overcome its major weaknesses, including cultural interactivity and transportation access, the ranking showed.

Buoyed by a rapid increase in foreign visitors from 6.81 million in 2013 to 8.87 million in 2014, Tokyo edged up the list in cultural interactivity, from sixth to fifth place. But, the Mori foundation concluded, there still remains a "vast gap" between Tokyo and the top three cities in terms of the number of tourists, hotels, museums and foreign residents.

Tokyo also failed to improve its accessibility, with the number of cities with direct international flights to Tokyo standing at 88, compared with 329 for No. 1 ranked London.

The city retained the top spot in economy, beating London by a slim margin of 3.1 points. But the negative impact linked to a weakening yen is set to eat into its economic prosperity in future rankings, Hiroo Ichikawa, a professor at Meiji University's Graduate School who helped compile the ranking, warned.

With the city locked in the same spot for eight years, "the next few years until the 2020 Olympics is our only chance to boost its ranking," Ichikawa said.

The challenges to overcome are clear, Ichikawa said, noting the number of hotels and international flights to Haneda and Narita airports must be increased.

Meanwhile, making more active use of home-sharing services, known as minpaku, among private home owners is key to alleviating the shortage of accommodation, said Former Economic and Fiscal Policy Minister Heizo Takenaka, who was also involved in compiling the ranking.

In this year's ranking, London held top spot for the fourth consecutive year since 2012, when it hosted the Olympic Games. Paris, which narrowly surpassed Tokyo to secure third place, was first in livability and accessibility, due largely to what the ranking called "its concentration of cultural, historical and traditional sites within a compact city center."