Border Guard Bangladesh Teknaf-2 Battalion Commander Lt Col SM Ariful Islam said the Rohingyas arrived in Cox's Bazar through Shah Porir Dwip point of the river on Friday evening.
Earlier in the morning, around 130 refugees arrived on boats, he said.
Friday's arrivals have taken the number of Rohingyas crossing the Naf river in three days to more than 900.
Ariful said they saw 10 rafts floating on the Myanmar side of the river in the morning.
Two speed boats, purportedly belonging to Myanmar border police, were also seen patrolling the area at the time, the BGB officer said.
"Eight of the rafts crossed the river in the evening," he added.
Bangladesh has sheltered around 1 million Rohingya refugees, including over 600,000 who have crossed the border since Myanmar army launched a crackdown following insurgent attacks on security forces on Aug 25.
Dozens of Rohingyas have died in the capsize of boats crossing the Naf river during the latest exodus.