The Taj could be a target

Local tourism official

An Indian air force base is located in the city.

"The Taj shines as far as 40 kilometre (24 miles) away, and is visible especially on moonlit nights. It could be a target," tourism official MS Juyal was quoted as saying by Associated Press.

Workers also have started building five bunkers to house armed guards around the monument, the agency reported.

A source from the Archaeological Survey of India told French news agency AFP that ladders had already been arranged around the monument and special ropes were being brought in.

"These are precautionary steps being taken to meet the situation in case it arises," the source said.

Security precautions

The Taj Mahal is revered as one of the world's most beautiful buildings.

The mausoleum took 22 years to build

Resting on the bank of the Yamuna River in northern India, it was built by the Mogul emperor Shah Jahan as a mausoleum for his wife, Mumtaz Mahal, who died in childbirth.

Construction began in 1631 and took 22 years to be fully completed.

Security was stepped up around the Taj following the 11 September attacks on America.

And in 1984 Sikh militants threatened to blow it up.