Bangladesh is limiting the movement of more than 400,000 Rohingya migrants who have fled from neighbouring Myanmar.
They must stay in fixed places allocated to them by the government and not travel elsewhere, police say.
Bangladesh also announced plans to build shelters for up to 400,000 people near the city of Cox’s Bazar.
The mainly Muslim Rohingyas have been fleeing a Myanmar government offensive since last month, which the UN says could amount to ethnic cleansing.
Rights groups have accused the military of burning Rohingya villages.
But the army says it is responding to attacks by militants and denies it is targeting civilians.
Meanwhile, a fresh diplomatic row between Bangladesh and Myanmar has broken out over alleged violations of Bangladeshi airspace in the past week.
In a statement, Bangladeshi police said Rohingyas would not be allowed to travel anywhere outside of their allocated homes, not even to live with family or friends.
Transport operators and drivers have also been urged not to carry refugees, with landlords told not to rent out any property to them.
Analysts say the government wants to stop the Rohingya from disappearing into the general population and to keep them visible, in the hope of returning them to Myanmar – or even a third country.
According to Bangladesh’s Daily Star newspaper, the new shelters will be on a site covering about 8 sq km (3 sq miles) of land, close to established camps which have been overwhelmed by arrivals from Myanmar.
A total of 8,500 temporary toilets will be built and 14 “makeshift warehouses” will be set up near the shelters, the paper says.
The new shelters are meant to be built within 10 days. (Courtesy BBC)