Theresa May has warned world leaders at the United Nations that they have a “duty” to stop the onward flow of migrants.

In a short speech in New York, the Prime Minister fiercely backed the right of other countries to control their borders, following an EU referendum campaign dominated by immigration.

Her words also go to the heart of tensions between EU countries, with southern European nations taking on unprecedented numbers of migrants, while member states further north tighten border controls.

She was addressing a special meeting as she claimed uncontrolled migration was exposing people to danger and reducing support for those fleeing war zones.

Mrs May said: “We need to be clear that all countries have the right to control their borders and protect their citizens and be equally clear that countries have a duty to manage their borders to reduce onwards flows of illegal and uncontrolled migration.

“We need to do more to help them do so.”

David Miliband: UK should take four times more refugees

At her first UN General Assembly gathering, she then explained how she thought leaders could successfully tackle a migration crisis that has put massive strain on Europe and been blamed as a key factor in the Brexit vote.

She went on: “Of course controlled legal and safe migration benefits our economies, and there is nothing wrong with the desire to migrate for a better life.

“But the uncontrolled migration we see today is not in the interests of migrants who are exposed to danger, not in the interest of the countries they are leaving, travelling through or seeking to reach, and not in the interest of refugees for whom resources and popular support are reduced.”

She said the first goal should be to ensure refugees claim asylum in the first safe country they reach, adding that the UN should “embed this as a principle”.

Politicians in northern and western Europe have demanded adherence to the principle as large numbers of refugees and migrants from Syria and North Africa have landed in Italy and Greece with the goal of heading for countries like Germany, France and the UK.

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

Mrs May said: “The current trend of onward movement benefits criminals gangs, endangers people and reduces the prospects of refugees ever returning home to rebuild their countries.

“So we must do far more to support the first safe countries themselves, assisting the refugees and host communities – an approach that is starting to work in Jordan, Lebanon and Turkey.”

She then said: “Second, we need to better distinguish between refugees and economic migrants.