A 2,500-strong "life jacket graveyard" has been created on Parliament Square this morning in a bid to raise awareness of the plight of refugees as world leaders meet at the United Nations in New York today (19 September).

The striking protest was organised by production company Snappin' Turtle and supported by the International Rescue Committee (IRC), Médecins Sans Frontières, World Vision, Migrant Voice and the United Nations Human Rights Council (UNHRC).

The life jackets used for the display were previously worn by both adult and child refugees and the organisers say they "reflect the lives and stories of those who experienced the treacherous and deadly stretch of sea from Turkey to the Greek island of Chios".

"Many jackets have been made by people smugglers from cheap materials which provide little or no support should someone enter the water," a spokesperson for Snappin' Turtle said.

The organisers said the display will be removed around 6pm tonight. The UNHRC has estimated that more than one million migrants and refugees reached Europe by sea in 2015. The group said almost 4,000 were feared drowned.

David Cameron's government promised to take 20,000 refugees from camps next to Syria by 2020. The UK's new Prime Minister Theresa May is expected to call for a better distinction between economic migrants and refugees when she speaks at the UN.

"Across the world today, we are seeing unprecedented levels of population movement and we need to work together to find a better response, which focuses our humanitarian efforts on those refugees in desperate need of protection and maintains public confidence in the economic benefits of legal and controlled migration," the Conservative premier said ahead of the high-level meeting.

"This is an urgent matter – more people are displaced than at any point in modern history and it is vital that we provide ongoing support for those people most in need of protection."