Tropical Cyclone Mocha has intensified to become "very dangerous", the World Meteorological Organization (WMO) said, warning of violent winds, floods and possible landslides in Bangladesh that could hit the world's biggest refugee camp.
The WMO's Clare Nullis told a press briefing that a storm surge of 2-2.5 metres over the weekend is likely to inundate low-lying areas of north Myanmar as well as parts of Bangladesh where flash floods and landslides are also possible.
"It's a very dangerous cyclone and ... it's associated with violent winds.
"There will be major impacts both ahead and after landfall for potentially hundreds of thousands of the world's most vulnerable people," she added.
The cyclone is expected to make landfall in Bangladesh on Sunday.
While a direct hit is not expected, the storm's path is set to affect Bangladesh's southeastern border district of Cox's Bazar where one million Rohingya refugees live.
Most of them fled there after a military-led crackdown in neighbouring Myanmar in 2017.
United Nations refugee agency spokesperson Olga Sarrado said preparations are under way for a partial evacuation of the camp, if needed.
The agency is also preparing tens of thousands of hot meals and jerry cans, she said.
The World Health Organization said it was pre-positioning some 33 mobile medical teams, 40 ambulances as well as emergency surgery and cholera kits for the camp.
In Myanmar, the WHO was pre-positioning 500,000 water purification tablets among other supplies which amount to the entire monsoon season stocks.
"If this turns into the level of cyclone we fear, we really need to be ready," the WHO's Margaret Harris told the briefing.
