New Delhi: The Taj Mahal will need nine years of mud packs to remove yellow stains from its white marble walls caused by air pollution, the Times of India reported on Wednesday.

Archaeologists said the lengthy period was needed to properly and safely clean particles from the four minarets and the main dome of the famed monument to love.

Authorities have taken numerous steps in recent years to try to protect the 17th-century monument from pollution coming from the busy city of Agra nearby, including banning local coal-powered industries.

The mud pack cleaning was announced last year, followed by a local ban on the common practice of burning cow dung for fuel, in order to reduce the carbon deposits on the Taj's walls.

The Times of India newspaper outlined an action plan by authorities after submitting a Right To Information request to access government documents.

The Taj — India's top tourist attraction — was built by Mughal emperor Shah Jahan as a tomb for his beloved wife Mumtaz Mahal, who died giving birth in 1631.

It has drawn a string of world leaders and royalty including former US president Bill Clinton, while Diana, the late British princess, was famously photographed alone on a marble seat there in 1992.