Myanmar immigration authorities have detained 106 Rohingya Muslims aboard a boat off Yangon, raising fears of a fresh wave of dangerous voyages after a 2015 crackdown on people smugglers.

An immigration officer said a boat was bound for Malaysia when authorities stopped it early on Friday morning some 30 kilometres south of Myanmar's largest city, Kyaw Htay.

The group boarded the vessel from internal displacement camps outside Sittwe, the capital of western Rakhine state, he said.

"Their destination was Malaysia. The boat was stopped after the engine failed," he said.

Rohingya and UN say Myanmar still not safe

Officials fear sea casualties may rise as more Rohingya refugees take riskier boat journeys to flee Myanmar. ( Reuters: Myat Thu Kyaw )

Tens of thousands of Rohingya have been confined to sprawling camps outside Sittwe since violence swept Rakhine in 2012.

UN agencies report more than 700,000 Rohingya fled a brutal army crackdown in the northern part of the state last year.

The Rohingya say soldiers and local Buddhists massacred families, burned hundreds of villages, and carried out gang rapes.

UN-mandated investigators have accused the Myanmar army of "genocidal intent" and ethnic cleansing.

Myanmar denies almost all of the allegations, saying security forces were battling terrorists.

Attacks by Rohingya insurgents calling themselves the Arakan Rohingya Salvation Army preceded the crackdown.

Officials say they are ready to accept Rohingya who want to return from Bangladeshi refugee camps.

But on Thursday, efforts to repatriate several thousand failed after refugees protested, saying they did not want to return.

UN officials and aid agencies also opposed the plan, saying conditions in Myanmar were not safe.

Neighbouring countries fear further sea casualties

Rohingya refugees in Bangladesh fear their safety will be at risk if they are repatriated to Myanmar. ( AP: Dar Yasin )

Officials and aid workers said last week dozens of Rohingya in Myanmar and Bangladesh had boarded boats to try to reach Malaysia in recent weeks after the end of the monsoon rains in early October.

Those who arrived on Friday were questioned on the top floor of a cyclone shelter, where women wearing headscarves, men, and children could be seen through the windows.

They were led to trucks as a phalanx of officials stood guard, women leading small children by the hand and some carrying small bags, before being driven away towards Yangon.

In a Facebook post, Aye Mya Mya Myo, a Lower House politician in Aung San Suu Kyi's ruling National League for Democracy party from Kyauktan, said there were 50 men, 31 women and 25 children in the group.

Early on Friday she posted pictures of a rickety boat crammed with people.

It resembled vessels the Rohingya typically use to escape Rakhine, where they are denied free movement and access to decent education and healthcare.

For years, Rohingya on both sides of the border have boarded boats organised by smugglers in the dry months between November and March, when the sea is calm.

The perilous journey to Thailand and Malaysia, often undertaken in overcrowded vessels, has cost many lives.

Thailand cracked down on the trade after discovering a series of mass graves in 2015, leading to a crisis when smugglers abandoned their human cargo and left boats adrift in the Andaman Sea.

Reuters