Police in Punjab are investigating whether a brick kiln owner held migrant workers and their children in debt bondage, after labourers and activists protested preliminary findings that there were no violations of labour laws...Forty people - from eight families, including adult workers and about a dozen children - were allowed to leave the kiln this week in Bathinda district in Punjab state after activists and other workers said they had been held against their will because the owner said they owed money...The workers in Bathinda were brought from neighbouring Uttar Pradesh state last October with advance payments of 5,000 to 10,000 rupees ($73-$146), said Gangambika Sekhar, an advocate with Volunteers for Social Justice, which came across the case on a field visit...They worked 14 to 16 hours a day with no access to basic amenities, and their wages were withheld, with only a subsistence allowance paid.