In nine seconds flat, two skyscrapers built illegally in the city of Noida near the Indian capital nine years ago will be razed by a controlled explosion on Sunday afternoon.

India's Supreme Court, in August last year, ordered the demolition of the 40-storey twin towers -- Apex and Ceyane -- built by private developer Supertech for violation of various building norms.

The twin towers will be India's largest ever highrises to be imploded at 2.30 pm (local time), using 3,700kg of explosives.

"I am getting goosebumps. I am a little nervous but confident as well," Utkarsh Mehta of Edifice Engineering, the company entrusted with the demolition job, told the local media this morning.

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Mehta said the explosion would trigger vibrations like that of a minor earthquake, which will be felt in a 30-40 metre radius of the twin towers. 

"The dust will take 15-20 minutes to settle down but we would need at least three to four months to clear the debris. Anti-smog guns have been pressed into action to clear the Noida sky," he said.

Local civic authorities have already ensured the evacuation of residents of all housing societies in the vicinity of the twin towers. Stray dogs have also been shifted to animal shelters, officials said.

"The nearby Noida Expressway will be shut for 45 minutes for the demolition. Hospitals in the city have been put on alert and 8-10 ambulances kept at standby in case of any untoward situation," a police officer said.

Demolitions of highrises are rare in India. Two years ago, authorities in the southern state of Kerala razed two luxury waterfront highrises for flouting environmental norms.