Hundreds of refugees are living in “inhumane” conditions in northern France with no toilets and only polluted rivers to wash in, the United Nations (UN) has warned.

"Increasingly regressive migration policies" and a lack of attention from national and international authorities has led to hundreds of displaced people living without adequate emergency shelter or proper access to drinking water in Calais and Dunkirk, experts said.

It is estimated that up to 900 migrants and asylum-seekers are currently based in Calais, 350 in Dunkirk and an unidentified number at other sites elsewhere along the northern French coast.

The French government has in recent months, taken temporary steps to provide access to emergency shelter, drinking water and sanitation for some refugees. Up to 200 migrants are currently being put up at a sports centre in Dunkirk.

But the UN experts stressed that these were not long-term solutions and warned that there was an absence of valid alternatives in the provision of adequate housing.

Leo Heller, the UN’s special rapporteur on the human rights to water and sanitation, said refugees in the region were facing an “inhumane situation”, with some living in tents without toilets and washing themselves in polluted rivers or lakes.

He added: “Some efforts have been made, but not enough. I am concerned that for every step forward, two steps are taken back. The situation along the northern French coast is emblematic of the need for much more attention from national and international authorities on this issue."

Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis Show all 7 1 /7 Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis The Solidarity With Refugees group said Saturday’s protest aimed to “show our Government and the world that Britain is ready to welcome more refugees”. Rex Features Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis People march through central London as they take part in a protest rally organised by Solidarity with Refugees in a bid to urge the Government to take more action on the migrant crisis Press Association Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis The protest comes days before world leaders meet to discuss crisis at UN General Assembly Press Association Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis Demonstrators made their way from Park Lane to Parliament Square in London on Saturday afternoon Press Association Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis Marchers chanted “refugees are welcome here” and waved banners reading “no-one is illegal” and “let’s help people” Press Association Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis The march was supported by charities and groups including the Red Cross, Asylum Aid, Save the Children, Hope Not Hate, Oxfam and the UN Refugee Agency Rex Features Refugees welcome here: Protesters demand UK resettle more migrants in response to refugee crisis In the wake of Alan’s death, David Cameron pledged to resettle 20,000 Syrian refugees in the UK over the coming five years but there have been additional calls to re-home those who have already reached Europe, as well as asylum seekers coming from other conflict zones such as Iraq and Afghanistan Rex Features

The warning comes almost a year-and-a-half after the demolition of the so-called Jungle camp in Calais, which was home to around 8,000 refugees before it was destroyed and more than 10,000 at its peak.

Following its closure, people were transported away from the region to reception centres across France, but the number of migrants re-entering the region has been gradually rising in recent months.

The UN’s special rapporteur on the human rights of migrants, Felipe Gonzalez Morales said the UN was concerned about "increasingly regressive migration policies and the inhumane and substandard conditions suffered by migrants".

He added: “Migrants, regardless of their status, are entitled to human rights without discrimination, including access to adequate housing, education, healthcare, water and sanitation as well as access to justice and remedies.

“By depriving them of their rights or making access increasingly difficult, France is violating its international human rights obligations.”

The experts also called for action to end harassment and intimidation of volunteers and members of non government organisations providing humanitarian aid to migrants. They urged France to fulfil its obligations and promote the crucial work of human rights defenders.

Annie Gavrilescu, field manager in France for charity Help Refugees, told The Independent: "A new worrying pattern is emerging, in Calais and across Europe, of criminalising aid workers. This comes in the context of significant aggression, violence and neglect that refugees themselves face from the police.

"However, any intimidation, harassment, criminalisation or hindrance of humanitarian aid is simply unacceptable and reminiscent of a very dark time in history. Human Rights Watch and a UN Special Rapporteur have also condemned this phenomenon.