A most wanted terrorist and the main conspirator behind the Ludhiana court bomb blast was arrested from Indira Gandhi International Airport here, an official of the National Investigation Agency (NIA) said on Friday.

Harpreet Singh alias "Happy Malaysia", a resident of Amritsar in Punjab who was carrying a reward of Rs 10 lakh, was arrested by the sleuths shortly after he arrived at the airport from Kuala Lumpur, the NIA spokesperson said.

He was arrested in a case relating to the massive bomb blast in the Ludhiana Court Building in December last year, which left one person dead and six others injured.

The case was initially registered on December 23, 2021, at Police Station Division-5, district Ludhiana Commissionerate, Punjab and re-registered by the NIA on January 13.

"Investigations revealed that Singh, an associate of Pakistan-based self-styled Chief of International Sikh Youth Federation (ISYF) Lakhbir Singh Rode, was one of the conspirators of the Ludhiana Court Building blast, along with Rode," the spokesperson said.

"Acting on the directions of Rode, he coordinated the delivery of the custom-made Improvised Explosive Device (IED), which had been sent from Pakistan to his India-based associates, that was used in the Ludhiana Court Complex blast," the spokesperson added.

The NIA said the arrested accused was also involved and wanted in various cases, including smuggling of explosives, arms and narcotics.

Earlier, the NIA had declared a reward of Rs 10 lakhs on Singh against whom a Non-Bailable Warrant from the Special NIA court had been issued and Look Out Circular (LOC) was opened.

Further investigations in the case are in progress, the spokesperson said.