Bangladesh has no scope to allocate more resources for its 1.3 million Rohingya refugees, Chief Adviser Muhammad Yunus said on Monday, urging the international community to find a sustainable solution to the crisis.

Children make up half the 1.3 million Rohingya refugees now living in Bangladesh, most of whom fled a brutal 2017 military crackdown in Buddhist-majority Myanmar that UN investigators called a "textbook example of ethnic cleansing".

Hosting the refugees has put a huge strain on Bangladesh, in areas from its economy and environment to governance, said Nobel peace laureate Yunus, the South Asian nation's de-facto prime minister.

"We don't foresee any scope whatsoever for further mobilisation of resources from domestic sources, given our numerous challenges," Yunus said at a conference.

He called for the international community to draft a practical roadmap for their return home.

"The Rohingya issue and its sustainable resolution must be kept alive on the global agenda, as they need our support until they return home."

His comments marked the eighth anniversary since more than 700,000 Rohingya arrived within a matter of days, turning the area around the southeastern coastal town of Cox's Bazar into the world's largest refugee settlement.

Tens of thousands of them held rallies on Monday in camps there, carrying banners and posters that proclaimed, "No more refugee life", "Stop Genocide" and "Repatriation the ultimate solution".

In Bangladesh, the refugees live in crammed bamboo shelters amid dwindling aid, closed schools and little hope of return.

"Over the last seven years, we have seen countless conferences, dialogues, and press statements, but nothing has changed for us," said Sayed Ullah, a Rohingya community leader who was among 40 refugees attending the conference.

"Our situation remains the same - we are still stuck in camps with no rights, no future, and no guarantee of returning home safely."

Over the past year another 150,000 have arrived from Myanmar's western Rakhine state, where fighting has escalated between junta troops and the Arakan Army, an ethnic militia drawn largely from the Buddhist majority.

The Myanmar military calls the operation against the Rohingya a legitimate counter-terrorism campaign in response to attacks by Muslim militants, not a planned programme of ethnic cleansing.

Attempts to begin their return home in 2018 and 2019 failed as the refugees, fearing prosecution, refused to go back.

"The world once supported us, but now it feels like we are left alone to struggle," said Hafizur Rahman, a refugee.

"In Rakhine, our brothers and sisters are still running for their lives and crossing into Bangladesh. If the world forgets us here too, what kind of future will be left for our children?"