• READ MORE: RBS under fire as UK jobs switched to India
Jagtar Singh Johal from Dumbarton, West Dunbartonshire, had a sack thrown over his head and was forced into a van by plain-clothes officers on November 4, the Sikh Federation UK said.
The 30-year-old was reportedly out shopping with his wife and cousin when the incident happened in Jalandhar in the state of Punjab.
He was in court on Sunday and is expected to appear again on Friday.
Mr Johal’s crimes reportedly include “running a magazine” in the UK of atrocities during the 1984 Sikh Genocide and “influencing the youth through social media”.
His brother and local MP have called for British authorities to intervene.
Mr Johal, who recently married, is said to have been in the country since October 2 for his wedding.
His whereabouts and condition remain unknown, the Sikh Federation said.
His elder brother Gurpreet Singh Johal said: “Unless the British authorities quickly step in this will guarantee a law-abiding British citizen will be illegally detained for some time and will not receive a fair trial. He should be immediately released and returned to the UK.”
Martin Docherty-Hughes, SNP MP for West Dunbartonshire, has been supporting the family.
He said: “I am deeply concerned about the circumstances of Jagtar Singh Johal’s arrest and imprisonment in India.
“This has been an extremely distressing time for my constituent’s family and I am doing everything in my power to support them as their Member of Parliament.
“The lack of information being given to Jagtar’s family by the police and judicial authorities in Delhi following his arrest is alarming.
“I have raised this as a matter of urgency with the British High Commission of India and the Foreign Office.
“I will also be contacting the Foreign Secretary and the Scottish Government to ensure that Jagtar and his family are not unfairly mistreated by the Indian authorities.
“This is an extremely serious matter and I hope my constituents will be fully supported in their efforts to secure a positive outcome.”