Two men named Adnan, linked to ISIS, were arrested from Sadiq Nagar and Bhopal for plotting a Diwali attack.
Police seized electronic devices, IED components, and videos pledging allegiance to ISIS.
The accused had scouted crowded south Delhi areas for the planned blasts, officials said.
Two suspected ISIS members were detained by Delhi Police on Friday for allegedly plotting a terror attack on Diwali in a populated part of the city, including a public park and a shopping centre in south Delhi, according to an official.
One of the accused ISIS members is from Delhi's Sadiq Nagar, and the other is from Bhopal. Both are named Adnan, according to a senior police officer.
"The arrests have averted a possible terror attack in Delhi," he said.
First, one operative was arrested from Sadiq Nagar on October 16, and later another was arrested from Bhopal.
Bhopal-resident Adnan was also arrested by Uttar Pradesh Police after he had allegedly threatened an Archaeological Survey of India (ASI) official on social media for surveying the Gyanvapi mosque.
"Preliminary investigation revealed that the accused were associated with ISIS, and were in the process of planning a major terror strike in Delhi. Electronic devices and incriminating materials have been seized from their possession," the officer said.
The suspects are being interrogated to ascertain their network and the extent of their plans, police said.
Incriminating information was found in their possession by police, including images of the locations where they planned to carry out a blast in Delhi and a video in which they make a "vow of allegiance" to ISIS.
According to Additional Commissioner of Police (Special Cell) Pramod Kushwaha, who was speaking at a news briefing, they also confiscated a watch they were using to create an IED timer and pictures of locations where they planned to get the supplies needed to manufacture the IED.
He claimed that they had scouted the areas of Delhi where they intended to launch an attack, including a public park and a shopping centre in South Delhi.
With PTI input.
