Six men have been detained on suspicion from the Pathankot railway station, Punjab Police officials said on Monday.
They were on board the Pooja Express from Jammu to Ajmer in Rajasthan, when security forces stopped the train in Pathankot late on Sunday and took them in custody.
The Punjab Police and their Jammu and Kashmir counterparts have been interrogating them along with other security officials.Security agencies are on alert in frontier districts of Pathankot and Gurdaspur in Punjab.
The Pathankot airbase of the Indian Air Force (IAF) was attacked on January 2, 2016. Seven people were killed in the attack.The area has defence establishments, including the frontier IAF base in Pathankot and the nearby Mamun Cantt of the Army.
Prior to the attack on the IAF base in 2016, militants had carried out an attack on Dinanagar town in Gurdaspur district.The Dinanagar attack took place on July 27, 2015. Six people, including the three gunmen, were killed in the attack.