Sheikh Badal (59) was arrested by the STF in the afternoon from near the Regional Passport Office in the city.
He has been charged with several offences including waging or attempting to wage war against the country, said an STF officer.
With this arrest, the STF has nabbed six suspected agents of Pakistan's ISI from the city.
Badal is said to be an accomplice of the five others and allegedly forged their passports.
Sleuths on November 14 had arrested Akhtar Khan alias Mohamad Javed and, following his interrogation, nabbed his brother Zafar Khan two days later.
Subsequently, the trio of Irshad Ansari, Asfaq Ansari and Mohammad Jahangir were arrested for their alleged role in leaking out strategic information to the ISI.
Besides a host of forged documents and fake Indian currency notes, police also seized hand drawn maps of defence PSU Garden Reach Shipbuilders and Engineers (GRSE) which builds warships for the Indian Navy.
"Badal worked as a tout for making passports and was instrumental in forging the passports of Akhtar and others," said the officer.
The officer said Badal also assisted Pakistani national Mohammad Ejaz, another suspected ISI agent held from Uttar Pradesh's Meerut.