Pollution is turning the Taj Mahal yellow, despite efforts by the Indian government to control air contamination around the poignant 17th century monument and keep it shimmering white, a parliamentary committee has said.

In a report to parliament this week, the standing committee on transport, tourism and culture said airborne particles were being deposited on the monument's white marble, giving it a yellow tinge.

The monument, in the northern city of Agra about four hours drive south of the capital, was built by Mughal emperor Shah Jahan as a mausoleum for his wife Mumtaz Mahal.

Authorities have made various attempts in the past to keep the area around the Taj Mahal pollution free, including setting up an air pollution monitoring station in Agra.

But the committee said that while air pollutants such as sulphur dioxide and nitrous oxide gases were generally within permissible limits, "suspended particulate matter" had been recorded at high levels except during the rainy season.

It suggested a clay pack treatment that is non-corrosive and non-abrasive be carried out to remove deposits on the marble. "The committee recommends that while undertaking any conservation activity at the Taj Mahal, abundant cautions should be taken to retain the original glory of the shimmering white marble used in this."

Attracting around 20,000 visitors every day, the monument was completed in 1648 after 17 years of construction by 20,000 workers.