Hundreds of people in India’s border region with Bangladesh have fled to the frontier, police said Wednesday, after the government ordered the construction of detention centres for undocumented Bangladeshi migrants and Rohingya refugees. Indian Prime Minister Narendra Modi’s Hindu-nationalist Bharatiya Janata Party (BJP) swept to power in West Bengal state in early May with a hardline policy to “detect, delete and deport” illegal migrants. India’s right-wing have long argued that illegal migration is a national security threat, and warned of changing demography in India’s border states.