MEXICO CITY/BOGOTA -- Mexico City has the most dangerous transport system for women out of 5 of the world's biggest commuter cities, according to a Thomson Reuters Foundation poll, with women saying other passengers often turned a blind eye to abuse.

The poll published on Thursday found about 3 in every 4 women in Mexico City were not confident about using the transport system without the risk of sexual harassment and abuse or sexual violence.

Cairo ranked a close second while less than 1 in 4 women in London, New York and Tokyo thought they were at risk of such abuse on public or private transport.

"Transport isn't safe and assaults happen all the time," Berenice Guerrero, a 22-year-old teacher from Mexico City, told the Thomson Reuters Foundation.

"I sometimes feel intimidated by men, and I try not to travel at night," said Guerrero, who spends 90 minutes a day commuting to work using the city's public buses and subway.

The survey conducted between Aug. 13-24 asked 1,000 women about safety, time spent travelling and cost of transport in the 5 of the world's largest commuter cities with underground train networks in 5 different cultural regions.

The poll of 200 women in each city comes as city authorities globally look at ways to ensure women have safe, efficient transport to reach work, education and healthcare which can help tackle poverty and boost the economy by including women.

In Mexico City 151 women said safety was their top transport concern while 141 women in Cairo saw it as the key issue.

In both cities about 3 in 4 women said they were not confident of travelling without sexual harassment or violence.

In Tokyo women also said safety was the top concern, ranked as such by 105 women, but only 15 percent thought they risked abuse or violence while on the move and strongly backed single-sex train carriages introduced in the city from 2000.

In New York the time spent travelling trumped safety as the top concern for women while in London women were more concerned about the cost of commuting.

CROWDING AND CHAOS

Erika Aguilar, a cleaner who uses Mexico City's bus and metro that carries about 5.6 million people on working days in the city of 21 million, said overcrowding led to assaults, including women groped, and fellow travelers looked away.

"If a woman is being harassed people don't want to get involved. People are afraid to," said Aguilar, 30. "There should be a strict limit on how many people are in each carriage."

Hadeer Khaled, 28, a research coder in Cairo, said authorities needed to be more pro-active to protect women.

"Once people know they are monitored and will be punished, they will behave well. But it's hard to impose control and monitor all kinds of transportation in Cairo," she told the Thomson Reuters Foundation.

Teresa Inchaustegui, head of the Mexican government's National Institute of Women (Inmujeres), said women feel safer in public than private transport which needed more regulation.

She said city authorities were ramping up efforts to improve safety for women on public transport with initiatives such as more cameras, more police, help booths and women-only carriages.

Other measures include public awareness raising campaigns aimed at encouraging men not to turn a blind eye when they witness violence against women, Inchaustegui said.

The poll, supported by Uber, found only about a third of women in Mexico City were confident or very confident anyone would help if they were being harassed compared to half in London.

"This is a problem we have tried to combat," Inchaustegui told the Thomson Reuters Foundation.

"Part of it could be to do with being afraid but the other part is due to complicity ... because they consider that men have the right to touch the woman they want."