Rohingya Muslims who have fled to Bangladesh's Cox's Bazar district live in "extremely challenging conditions" with little sign of hope, a UN envoy said Thursday.

Christine Schraner Burgener, the UN secretary-general’s special representative for Myanmar, was briefing the Security Council on her recent visits to Myanmar, Bangladesh and other destinations in the region.

According to a statement released by the UN on her briefing, Burgener said 18 months have elapsed since violence in Myanmar’s Rakhine State forced hundreds of thousands of Rohingya and others to flee their homes, including to neighboring Bangladesh.

“While Bangladesh and host communities have been very generous, we cannot expect this to continue indefinitely,” she said.

She said the recently launched United Nations Joint Response Plan for 2019, aimed at supporting both refugees and host communities, needs "urgent" funding.

Burgener said a number of priority steps also needed to be taken, including ending the violence in Myanmar, facilitating unfettered access to affected people, addressing the root causes of tensions and enabling inclusive and sustainable development.

She said military and civilian tensions persist in Myanmar ahead of general elections in 2020.

Expressing concern that heavy fighting with the Arakan Army will further impact efforts towards the dignified, voluntary return of refugees, she also appealed to both sides to ensure the protection of civilians and uphold their obligations under international law.

The Rohingya, described by the UN as the world's most persecuted people, have faced heightened fears of attack since dozens were killed in communal violence in 2012.

According to Amnesty International, more than 750,000 Rohingya refugees, mostly women and children, have fled Myanmar and crossed into Bangladesh after Myanmar forces launched a crackdown on the minority Muslim community in August 2017.

Since Aug. 25, 2017, nearly 24,000 Rohingya Muslims have been killed by Myanmar’s state forces, according to a report by the Ontario International Development Agency (OIDA).

More than 34,000 Rohingya were also thrown into fires, while over 114,000 others were beaten, said the OIDA report, titled "Forced Migration of Rohingya: The Untold Experience."

Some 18,000 Rohingya women and girls were raped by Myanmar’s army and police and over 115,000 Rohingya homes were burned down and 113,000 others vandalized, it added.

The UN has also documented mass gang rapes, killings -- including of infants and young children -- brutal beatings and disappearances committed by Myanmar state forces.

In a report, UN investigators said such violations may have constituted crimes against humanity.