Police have cordoned off the area and all retail outlets of sandstone dealers are being raided by the CBI.
Meanwhile, an emergency meeting has been convened by the Ministry of Home Affairs to assess the situation. A Ministry official confirmed that the site where the tower once stood was now totally bare.
The hand of terror outfits like Al-Qaeda is not being ruled out, he said.
The loss was discovered by caretaker Ghumman who told reporters he had no clue where the heritage structure was.
"The Minar was there as usual when I went to sleep last night. This morning when I woke up it had vanished."Historians feel that it would be next to impossible to transport the Qutab Minar as it is. The only other alternative of taking it down brick-by-brick would have taken even a dedicated army months to accomplish.
According to an ASI official, all this might be the handiwork of a master illusionist like David Copperfield who has hypnotised people into "not seeing" the Qutab Minar. Investigations are on, he said, adding that the loss of the Minar "would be a great loss for India."
Sultan Qutb-ud-Din Aibak laid the foundation of the Minar in AD1199 and it was completed by his successor Iltutmish. At 72.5 metres, the red sandstone structure is, or rather was, the highest stone tower in India.(T2N2)