Health officials in the Mexican capital are hoping to get residents in shape by offering free transport to passengers who perform some light exercise.

Dozens of stations in Mexico City's metro system have been equipped with special machines that dispense a token for a free ride to passengers who perform 10 squats.

The so-called "health stations", which also tell passengers how many calories they have burned, are a novel way for health chiefs to draw attention to Mexico's mounting obesity levels.

According to official figures, 70 per cent of adults and nearly a third of children are overweight or obese in the country – a higher rate than the United States and Australia.

"Levels of excess weight and obesity concern us greatly. For me, it's the number one public health problem," the capital's health secretary, Jose Armando Ahued Ortega, said as he introduced the project, devised by leftist mayor Miguel Angel Mancera.

Thirty of the squat-counting machines have been installed across the city.

The machines will also hand out pedometers to the first 80,000 users to help them track their energy output.

With more than five million daily users, the subway is a vital means of transport in the city.

Metro tickets in December 2013 went up from three to five pesos ($0.26 to $0.43), generating fierce criticism from commuters in a country where the minimum wage is 70 pesos ($6.05) a day.

A similar campaign in Russia in 2013 offered a free subway ride in exchange for 30 squats.

AFP