Dr. Jagjit Singh Chauhan, a former regional finance minister of Punjab state, spearheaded an often-violent campaign for an independent Sikh homeland known as Khalistan in the 1980s. The movement died in the 1990s.
Chauhan arrived in India aboard a British Airways flight early Wednesday, accompanied by officials from Amnesty International. He had lived in London for the past two decades.
Chauhan was immediately whisked away by Indian security agencies for interrogation and released in time to board a train to Chandigarh, the twin capital of the Indian states of Punjab and Haryana.
He was wanted in a number of cases relating to secessionism in Punjab. In the '80s, he floated a Khalistan government in exile and printed Khalistan passports and currency.
Chauhan was unable to return to India despite his interest in doing so as the Indian government had blacklisted him and revoked his passport.
The Punjab and Haryana High Court stepped in on May 29, however, and directed the government to provide Chauhan with travel documents to enable him to visit the country.
"Returning to one's own country is the fundamental right of a citizen and as such the assessment of intelligence agencies in view of Dr. Chauhan's stand in favor of 'Khalistan' could not stand in the way of an individual's right," the court said in its judgment.
Earlier Wednesday, the former doctor's application for anticipatory bail was rejected by the high court on technical grounds.
Speaking to United Press International, Chauhan said he would keep the Khalistan movement alive "democratically.
I have always been against violence and continue to remain so", he said.
He said he would meet with Sikh leaders, including Punjab Chief Minister Parkash Singh Badal to "chalk out his future course of action."
"Many things have changed in the country in the two decades that I have not been here," Chauhan said. "Both India and Punjab have progressed tremendously."