Patrols have been stepped up along the frontier with India's West Bengal state, where border guards say they have been ordered in recent weeks to steer Rohingya into Bangladesh.
Tariqul Hakim, an area commander of the Border Guard Bangladesh, said Rohingya could be seen gathering opposite the Putkhali frontier post, where just a narrow river divides the two countries.
"We have stepped up surveillance and patrols so that no Rohingya can be pushed into our territory," Lieutenant Colonel Hakim told AFP.
An estimated 536,000 refugees have crossed since August 25, fleeing violence in western Myanmar described by the United Nations as ethnic cleansing.
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An Indian border guard in West Bengal told AFP that patrols had previously turned over all Rohingya intercepted at the frontier to local police.
"But now our directions are very clear, and that is to push all Rohingya into Bangladesh," he told AFP on condition of anonymity.
Bangladesh already hosts at least 800,000 Rohingya, including those who fled earlier crackdowns in Myanmar, and does not want to accept any from India.
It is trying to repatriate the Rohingya to Myanmar. But the stateless Muslim minority are reviled in the mainly Buddhist nation and considered to be illegal immigrants.
The unprecedented influx of refugees has put immense pressure on Bangladeshi authorities and charities, who have described the crisis as one of the world's most pressing humanitarian emergencies.