The National Investigation Agency (NIA) has arrested a seventh person in connection with the brutal killing of tailor Kanhaiya Lal in Rajasthan's Udaipur last month, a spokesperson said on Sunday.

The spokesperson said Farhad Mohammad Sheikh, alias Babla, was arrested on Saturday evening.

He was a "close criminal associate" of Riaz Akhtari, one of the two main accused, and took an active part in the conspiracy to kill the tailor, the spokesperson said.

Kanhaiya Lal was killed with a cleaver inside his tailoring shop on June 28.

The gruesome attack by Riaz Akhtari, who is also referred to as Riyaz Attari, on the tailor was recorded on a phone by Ghouse Mohammad, and the video was posted online. They said in a video later that they hacked Lal to death to avenge an alleged insult to Islam.

The duo were arrested within hours of the killing.

Besides the duo, against whom the evidence is a self-shot video, the security agencies nabbed two more persons -- identified Mohsin and Asif -- who are alleged to be a part of the conspiracy to spread terror amongst the public at large.

Two more accused -- Mohammed Mohsin and Wasim -- were arrested subsequently for being part of the criminal conspiracy and helping the two main accused in carrying out recce of the tailor's shop.

The probe agencies have claimed to have found several Pakistani numbers on their WhatsApp accounts and said that one of the accused was part of some secret groups ostensibly meant for religious activities.

In one of these groups, it was alleged that Ghouse had been asked to do "something spectacular" to avenge the insult to Islam and the officials believed that this could be the turning point where the "barbaric" act of killing the tailor could have been hatched.

They said that Mohsin's place was used for sharpening the cleaver used in the killing and Asif had helped in carrying out the recce of the tailor's shop.

The NIA had on June 29 re-registered the case under the anti-terror Unlawful Activities (Prevention) Act after taking it over from the Rajasthan Police.

The case was initially registered at Dhanmandi police station in Udaipur.

"NIA has re-registered a case under sections 452, 302, 153(A), 153(B), 295(A) and 34 of IPC and sections 16, 18 & 20 of UA(P) Act, 1967 against accused who have conspired, planned and committed the heinous murder...," the agency spokesperson had said.

"The accused persons had also circulated a video of the criminal act in the social media claiming responsibility for the murder in order to trigger panic and strike terror among the masses across the country," the spokesperson had said.