India's Supreme Court today expressed concern over the change of colour of the 17th century white marble Taj Mahal in Agra saying the monument had become yellowish earlier and is now turning brownish and greenish.

The Apex Court suggested that the Indian government takes help of experts from India and abroad to first assess the damage and then take steps to restore the world heritage monument.

"We don't know whether you have or perhaps don't have the expertise. Even if you have the expertise, you are not utilising it. Or perhaps you don't care," a bench comprising Justices M B Lokur and Deepak Gupta said.

"Perhaps, we need some expert organisation from outside India, unless there is a decision that the Taj has to go," the bench said sarcastically, adding "you can get experts from India as well as from outside."

The Apex Court saw the photographs placed before it by petitioner M C Mehta, an environmentalist, and asked Additional Solicitor General A N S Nadkarni, who was representing the Indian government, as to why the colour of Taj Mahal has changed.

"First it was yellow and now it is becoming brown and green," the bench observed.

Nadkarni told the bench that the management of Taj Mahal has to be done by the Archaeological Survey of India.

Mehta has filed the plea seeking protection of the Taj from the ill-effects of polluting gases and deforestation in and around the area.

The Apex Court fixed the matter for further hearing on May 9. It has been monitoring developments in the Taj area to protect the monument, built by Mughal emperor Shah Jahan in the memory of his wife Mumtaz Mahal in 1631.