NIA took custody of Showkat Ahmed Bhat, a resident of Pulwama about 31 kms from Srinagar, after he was detained by Jammu and Kashmir police.
NIA said 36-year-old Bhat was allegedly involved in transporting a group of four LeT terrorists Mohammad Naved Yakub, Zhargham alias Mohammed Bhai, Abu Okasa and Noman from Baba Reshi in Baramulla district to south Kashmir soon after they infiltrated into India from PoK.
The group split into two. One group attacked BSF convoy in Udhampur on August 5, during which Naved was arrested and his associate Mohammed Noman alias Momin was killed.
Showkat will be produced before the Special NIA Judge, Jammu for obtaining his custody for further investigation.
This is the third arrest made by NIA in this case, so far.
Earlier, besides Naved, Khursheed Ahmed, who ferried the terrorists to Jammu on two occasions, have been arrested in this case.
Naved has given his confessional statement before a judge in Jammu while Khursheed would be produced soon with a request to shift him to Delhi for scientific investigations including a lie detector test.
When Naved and his three associates sneaked into India on June 2, two top LeT commanders came all the way from Islamabad to see them off besides handing over arms and ammunition.
According to a dossier prepared to be given to Pakistan during the now-cancelled National Security Advisors level talks, Naved, after completing four months' training at Daura-e-Lashkar camp in Muzaffarabad in PoK on May 20 this year, left in a Hyundai open supply vehicle of LeT, along with Mohammed Bhai, Mouwaz, Abu Ali and one Ahmed.
The group reached 'Halen Det' at Forward Kahuta next day.
The 'Halen Det' camp was supervised by one Qital Sindhi. The group was received by Abu Ukasha, a person named Muslim and another person Zarrar.
"On May 25, Sajid aged about 45 years, the LeT operations commander for South Kashmir and Hanzla Asnan, also aged about 45, the LeT commander for North Kashmir along with Noman, a resident of Bahawalpur (terrorist killed in the Udhampur attack) arrived in a car from Islamabad at Halen Det Mosque, Forward Kathua, Pakistan occupied Kashmir," the dossier says.
Noman was the "leader of the group" of terrorists who sneaked into India.
The LeT commanders handed over to each of the four terrorists an E-Trax GPS device, a wireless set, a compass, a printed map on flex sheet, an AK-47 with six magazines, two hand grenades, a digital watch, a black-coloured track suit, a pair of shoes and Rs 50,000 of Indian currency.
"In addition, the group carried two mobile handsets but they were not used by them," the dossier says.