(Updates with a fresh arrest)

nchkula December 17, 2012 20:25 IST In the second arrest in as many days in the Samjhauta Express blast case and fifth in all,)Dhan Singh, a prime suspect, was today arrested by the National Investigation Agency(NIA) from Madhya Pradesh.

The arrest came even as the NIA told a Panchkula court that Rajender Chaudhary alias Pehalwan, who allegedly planted a bomb in Pakistan-bound Samjhauta Express in 2007, played a key role in the entire operation, claiming he was "instrumental" in preparing and procuring the explosive devices.

Pehalwan, in his mid-30s, was arrested by the National Investigation Agency (NIA) on Saturday night from Nagda, 50 km from Ujjain in MP, where he was living under an assumed name.

Chaudhary has been sent to 12 days custody of NIA by the court in Panchkula, near Chandigarh, which is hearing the matter.

Singh, who was arrested from Chitrakoot along MP-UP border following intelligence inputs, is also suspected to be involved in the 2008 Malegaon blasts case, sources said in New Delhi.

Singh, who is one of the alleged conspirators in the Samjhauta case, was known as 'Swamiji' in Chitrakoot, they said.

It is the fifth arrest in the case. The NIA has already arrested Kamal Chauhan, Aseemanand and Lokesh Sharma for their alleged involvement in the blast.

A huge explosion that ripped through Samjhauta Express near Panipat in Haryana on February 18, 2007 and a subsequent fire in the coaches had led to the loss of 68 lives and injuries to 12 train passengers, including women and children.

Amid high drama while being taken inside the Court for the in-camera proceedings, Pehalwan claimed before a group of mediapersons his involvement in planting the explosives, but after the court hearing ended, he retracted and told the journalists he had been taken into custody "under a conspiracy."

The initial investigation into the bomb blast was conducted by the Government Railway Police and Special Investigation Team of Haryana Police but subsequently NIA took over the case on July 29, 2010 following a directive by the Home Ministry.