The head of Paris’s regional transport network on Monday conceded that the city’s metro system is nearly impossible for disabled individuals to navigate, just days before the French capital hosts the Paralympics.

With the Games kicking off Wednesday, the inaccessibility of metro transport for disabled visitors has emerged as a significant concern.

Paris’s metro system, which first opened in 1900, has expanded to become the busiest in the European Union, featuring more than 300 stations across 16 lines and serving over 4 million passengers daily.

However, only 29 stops are wheelchair-accessible.

The city's historic metro lines "remain the weak spot" in terms of accessibility, said Valerie Pecresse, who, as president of the Paris region, also oversees its transport network.

She called for a massive effort to address the problem.

While all buses running in central Paris can accommodate wheelchairs, only 25% of rail services – metros, trams and the RER suburban mass transit system – are accessible, she said.

Most of the metro could be modernized for accessibility, although it would take 20 years and cost between 15 billion and 20 billion euros ($16.7 billion to 22.3 billion) in investment, she told reporters.

Such an effort "could become the great project of this decade," she said, dubbing the idea "A Metro for All."

Paris's preparations for the Paralympics, which run through Sept. 8, have highlighted the lack of accessible transportation in the French capital.

However, Pecresse said some solutions have been implemented for the Games, including about 100 minibuses to transport disabled visitors to competition venues.

A smartphone app will also be available to help them plan their journeys.

Authorities expect up to 300,000 daily visitors during the Paralympics, about half the number anticipated for the Olympics.