India's tallest rubbish mountain in New Delhi is on course to rise higher than the Taj ­Mahal in the next year, becoming a fetid symbol for what the UN considers the world's most polluted capital.

Hawks and other birds of prey hover around the towering Ghazipur landfill on the eastern fringe of New Delhi; stray cows, dogs and rats wander at will over the huge expanse of smoking filth.

Taking up the area of more than 40 soccer pitches, Ghazipur rises by nearly 10 meters a year with no end in sight to its foul-smelling growth.

According to East Delhi's superintendent engineer Arun Kumar, it is already more than 65 meters high. At its current rate of growth, it will be taller than the iconic Taj in Agra, some 73 meters high, in 2020.

India's Supreme Court warned last year that red warning lights will soon have to be put on the dump to alert passing jets.

Ghazipur was opened in 1984 and reached its capacity in 2002 when it should have been closed. But the city's detritus has kept on arriving each day in hundreds of trucks.

Fires, sparked by methane gas coming from the dump, regularly break out and take days to extinguish.

Shambhavi Shukla, senior researcher at the Center for Science and Environment in New Delhi, said methane belching from the garbage can become even more deadly when mixed with atmosphere.