The accused, identified as Naeem, was arrested from Meerut on Thursday night, they said.
He was allegedly involved in supplying weapons to the 10 men arrested by the NIA in the case, the officials said.
On December 26, the probe agency busted a suspected ISIS-inspired terror group and arrested 10 men, including a ‘mufti’ from Amroha in Uttar Pradesh, who it said were planning suicide attacks and serial blasts targeting politicians and government installations in Delhi and other parts of north India.
The NIA also recovered a locally-made rocket launcher, material for suicide vests and 112 alarm clocks to be used as timers during its searches in Delhi and Uttar Pradesh.
A Delhi court allowed the NIA 10 days custodial interrogation of the men after it produced them before it on December 27.
“The members were in an advanced stage of preparation. They were just waiting for the successful assembly of bombs and wanted to hit multiple locations using remote controlled IEDs and pipe bombs and carry out fidayeen attacks using suicide vests when needed,” a senior NIA official said.
The group is called ‘Harkat ul Harb e Islam’, which loosely translates into war for the cause of Islam, he said.
The “highly-radicalised module” of youths in the age group of 20-35 years is completely self-funded and no criminal antecedent of its members surfaced so far, the official said.
Those arrested include the alleged mastermind, 29-year-old Mohammed Suhail, a ‘mufti’, or a Muslim legal expert empowered to give rulings on religious matters, from Amroha in western UP, an engineering student of Amity University in Noida and a third year graduation student in humanities in a university in Delhi as well as two welders, he said.