Nearly 500,000 people in the Democratic Republic of Congo have been left without clean drinking water after a volcano erupted, the charity Médecins Sans Frontières (MSF) has warned.

It says because cholera is endemic and poses a great threat there is an urgent need to provide people in the eastern city of Goma with safe drinking water.

A reservoir and pipes were damaged when Mount Nyiragongo erupted on 22 May.

Hundreds of thousands of people are still unable to return to their homes.

"We are assisting the immediate needs of displaced people, but it is not enough," said Magali Roudaut, MSF head of mission in DRC.

"We demand urgent support of other humanitarian organisations to assist people."

MSF said its teams were providing medical services in the nearby town of Sake, "where between 100,000 and 180,000 people are gathering in churches, schools, mosques, and on the streets".

Mount Nyiragongo, 10km (six miles) from Goma, spewed lava 10 days ago, killing 32 people, the UN says.

There have been many tremors since one of the world's most active volcanoes erupted.

In an effort to assess the level of risk experts have flown drones into a second smoking crater where molten lava has been spitting out of the ground.