Police on Thursday detained 12 Bangladeshi nationals travelling in Howrah-Hyderabad East Coast Express.
"We have detained them for questioning and trying to contact the police in West Bengal to ascertain their antecedents," a senior police officer told PTI.
It is suspected that they boarded the train from Howrah, he added.
"Acting on a tip-off, we launched a special drive in the train from Warangal, over 150 km from here," he said.
"We have to check up antecedents of detained persons and they would be released once the investigation are over," he said.