Myanmar has returned dozens of Rohingya to camps in conflict-wracked Rakhine state, officials said Thursday, after arresting them at sea as they tried to flee what rights groups brand as "apartheid" conditions.

A group of 42 Rohingya Muslims -- including two children -- was detained last Thursday offshore of Bogale in Ayeyarwady region, local police told AFP.

The long-persecuted Rohingya are widely regarded as illegal immigrants in Myanmar, refused citizenship and unable to travel freely.

One of the group tested positive for coronavirus, but the rest arrived Wednesday night in Kyaukphyu in central Rakhine state, local MP Ba Shein told AFP.

His constituents were "very worried" by the coronavirus risk, he said.

Local officials said the group was due to be sent by boat to camps further north on Friday.

Military operations in 2017 forced some 750,000 Rohingya to flee from northern Rakhine to Bangladesh in violence that now sees Myanmar facing genocide charges at the UN's top court.

But around 600,000 more Rohingya remain in Myanmar, living in what Amnesty International describe as "apartheid" conditions. 

Kyaukphyu is one of many strictly segregated towns with its Muslim population of over 1,000 people confined to a camp since inter-communal violence in 2012.

It is mainly home to Kaman Muslims, a minority that -- unlike the Rohingya -- is officially recognised in the Buddhist-majority country, even though they  also suffer discrimination.

The detained Rohingya were taken to the Muslim camp, where its inhabitants were told they had no choice but to accept them, one resident told AFP, asking not to be named.

"They had been travelling without sleep or food...so we agreed to let them come in," he said, adding his community was scared it would be even more stigmatised because of the coronavirus risk.

"We're already facing huge problems --  they (the authorities) are just causing more trouble for us."

Hundreds of Rohingya have been arrested while trying to flee Rakhine state and seek refuge in other countries, many spending months or even years behind bars.

Burma Human Rights Network (BHRN) last week called for more international pressure on Myanmar in its report titled "Nowhere to Run in Burma: Rohingya trapped between an open-air prison and jail".

Executive Director Kyaw Win decried the "weaponisation" of Myanmar's legal system "against an entire ethno-religious group born and living in the country for generations".