DHAKA:Bangladesh has begun preparations to move thousands of Rohingya refugees to a remote island off its coast, officials said on Wednesday, despite opposition from many refugees and human rights groups who have termed it an "island detention center".

Bangladesh says transporting refugees to Bhasan Char – a Bay of Bengal island hours from the mainland by boat – will ease chronic overcrowding in its camps at Cox’s Bazar, which are home to more than 1 million Rohingya, members of a Muslim minority who have fled neighboring Myanmar.

Humanitarian and human rights groups have urged a halt to the move, saying the island, which emerged from the sea 20 years ago and has never been inhabited, is flood prone and vulnerable to frequent cyclones, while the government has not allowed the United Nations to carry out a safety assessment.

A senior local official, who spoke on condition of anonymity, told Reuters in a message "many families" had been moved out of the camps as of Wednesday night, but declined to state a number.

More than 730,000 Rohingya fled Myanmar in 2017 following a military-led crackdown that the U.N has said was executed with genocidal intent. Myanmar denies genocide and says its forces were targeting Rohingya militants who attacked police posts.

A briefing note by an international humanitarian organization seen by Reuters said hundreds of refugees identified by officials as willing to go to the island were taken to a transit center on Wednesday, with some offered incentives including cash payments.

Mohammed Shamsud Douza, the deputy Bangladesh government official in charge of refugees, said housing had been built for 100,000 people and authorities want to relocate them during the November to April dry season when the sea is calm.

"We will not force anyone to go there," he said by phone, but did not comment on whether incentives had been offered.

The U.N said in a statement it had been given "limited information" about the relocations and was not involved in preparations.

Louise Donovan, a spokeswoman, told Reuters the government had not given the U.N permission to carry out technical assessments or to visit refugees already held there.

More than 300 refugees were brought to the island earlier this year after an attempt to flee Bangladesh for Malaysia by boat failed and they were stranded at sea for months. They have said they were being held against their will and complained of human rights violations, some resorting to hunger strikes, according to rights groups.

"Rohingya in the camps in Cox’s Bazar face many issues and problems, and the camps are overcrowded and imperfect, but moving people to an isolated island where they have no protection or support from international humanitarian agencies or freedom of movement is not the answer," said Ismail Wolff, regional director of the nonprofit rights organization Fortify Rights.

"At present, it’s an island detention center."