DHAKA (Reuters) - Landslides and related incidents triggered by pre-monsoon rain in southeast Bangladesh have killed at least 12 people since Monday, including two Rohingya Muslims, and the government said it was moving fast to relocate tens of thousands of people.

The deaths happened in the districts of Cox’s Bazar and Rangamati - both bordering Myanmar from where hundreds of thousands of Rohingya have fled a military crackdown - due to incessant rain over the past three days, government officials said on Tuesday.

International aid agencies said there was a big risk of an outbreak of waterborne diseases in the Rohingya camps in Cox’s Bazar, where nearly a million people live, mostly in shacks made of bamboo and plastic sheets that cling to steep, denuded hills.

“Sodden and unstable hills have collapsed over the weekend, destroying latrines. At lower levels, water from flash floods is washing over latrines, carrying sludge through the camps,” said Sanjeev Kafley, head of the Cox’s Bazar office of the International Federation of Red Cross and Red Crescent Societies.

“We’re already seeing increases in acute water diarrhea, and the risk of an outbreak of waterborne diseases is now a serious likelihood.”

One of the two Rohingya casualties in Cox’s Bazar was a two-and-half-year-old boy who died when a mud wall fell on him and his mother. The injured mother is in hospital. A Rohingya man was killed when a tree, weakened by rainfall, fell on him.

The number of Rohingya in Bangladesh has swelled since last August, when an army operation in Myanmar following Rohingya insurgents’ attacks on security forces prompted an exodus to Bangladesh.

Mohammad Shamsuddoha, a senior official in Bangladesh’s refugee relief and repatriation commission, said that around 1,500 shacks have been damaged or destroyed since the weekend due to the rain.

Nijhum Rokeya Ahmed, from the Bangladesh Meteorological Department, said there was a possibility of medium to heavy rain over the next 24 hours that could trigger further landslides in districts like Rangamati and Cox Bazar.

The government is working with international aid agencies to quickly relocate an initial group of 100,000 Rohingya from the camps, said Mohammad Shah Kamal, the top civil servant in the Ministry of Disaster Management and Relief, who was visiting Cox’s Bazar.

As of the first week of June, more than 28,000 refugees had been relocated, according to the Inter Sector Coordination Group that oversees relief work in the camps in Cox’s Bazar.

Last week, the United Nations High Commissioner for Refugees said relocation was a challenge due to the lack of alternative flat land. Around 200,000 people have been identified as being at high risk.

“Since we don’t have any place here we have to move them to Bhasan Char island and by September this year the relocation will be possible,” said Kamal, referring to the much-criticised plan to shift the Rohingya to a remote Bay of Bengal island being developed.

In the hilly district of Rangamati, where 10 Bangladeshis have died, officials said rescue and relief teams were struggling to reach people due to difficult terrain.