Image copyright AFP/Getty Images Image caption Sagaing is one of four districts in Myanmar to be declared a disaster zone by the government

The death toll from floods in Myanmar is expected to rise over the coming days, the United Nations has warned.

Four western regions have been declared disaster zones after heavy floods, caused by monsoon rains, left at least 27 people dead.

But rescue teams have not yet reached many areas and are still awaiting reports on the worst-hit regions.

In the neighbouring eastern Indian state of Manipur, a landslide buried a village, killing at least 21 people.

Media playback is unsupported on your device Media caption BBC Weather reporter Ben Rich explains why Myanmar has seen such exceptional rainfall

Heavy rains are normal in monsoon season, but many people in Myanmar - also known as Burma - told the BBC that the rains were particularly strong in recent weeks.

Wind and rain from Cyclone Komen added to damage.

On Sunday, the UN Office for the Coordination of Humanitarian Affairs said some 156,000 people were affected by the floods in 12 districts but the total could be "significantly higher".

Media playback is unsupported on your device Media caption A journalist with the Democratic Voice of Burma did a live news report while standing in chest-high flood waters

The UN also said:

there was "extensive damage" to camps housing 100,000 Rohingya Muslims in Rakhine state

the city of Kalay, with 400,000 people, is accessible only by air

at least 100 houses were destroyed by landslides in Chin state

Haka town in Chin state, with a population of 40,000, is inaccessible by road due to landslides

On Saturday, Mg Mg Khin from Myanmar's Red Cross told the BBC the country was facing "a big disaster".

Heavy rains are expected in many states, including Chin, Rakhine and Magwe, over the next two days, forecasters say.

Thousands of people are sheltering in Buddhist monasteries, but one report said people from the Rohingya Muslim minority were turned away from some shelters.

The Burma Times said security forces turned away Rohingya Muslims from abandoned schools and community centres in Rakhine.

More than half a million acres of rice paddy fields have been flooded, the Ministry of Agriculture and Irrigation said.

Image copyright AFP/Getty Images Image caption Many in Myanmar said the rains are the worst in many years

Image copyright EPA Image caption The rain began in mid-July and Burmese have been fleeing badly-hit areas

Image copyright AFP/Getty Images Image caption Rescue efforts in Manipur have been hampered by floods and landslides

The landslide in Manipur state hit a remote village in Chandel district, bordering Myanmar, early on Saturday.

Rescue teams are expected to reach the area only on Sunday because of heavy rains and landslides, a local MP said.

Continuous rain in recent days has washed away bridges and roads and left thousands homeless, India's NDTV reported.

Elsewhere, floods in Vietnam left at least 17 people dead and in western Nepal, some 36 people were killed after torrential rain triggered landslides.