However, her attempt to cut queues outside women's loos through the restroom equality bill is meeting resistance.

"You're probably talking about tens of millions of dollars," Robert Bookman, a lawyer for the New York Nightlife Association, told a city council hearing.

"The expense needs to be looked at for the entire city. The lines I see are much more than two-to-one, frankly, so what happens when we go through all this and you don't solve the problem?"

Ms Clarke, whose bill would place requirements on stadiums, bars, cinemas and theatres, was not to be deterred. "I think we can all agree that when you're standing in a line, there's nothing more serious at that moment than answering that call," she said.

Bill de Blasio, a city councillor and chairman of the general welfare committee when the proposal was introduced last year, said: "This is about fairness. If there's anything that has to do with the general welfare of people, it's this issue."

Several states have already adopted similar laws, and the Equal Employment Opportunity Commission has delivered lawsuits against companies that have failed to provide proper facilities, prompting some men to complain of "potty police".

Studies by various universities have shown that women take almost twice as long as men to use the lavatory: 45 seconds on average for men, compared with 79 seconds for women, according to researchers who stood outside motorway service toilets. The extra time was generally spent removing and replacing clothing, accompanying children and washing hands.

A study by the University of Chicago found that women were three times more likely than men to wash their hands after the event.