More than 50 faith leaders around the world are calling on the international community to step up protection for people displaced from their homes by violence, conflict and disasters.

In a letter to the Guardian, Christian, Islamic and Jewish leaders have urged governments attending the UN general assembly in New York next week to support a plan of action to prevent the forcible displacement of people and strengthen the protection of those who become refugees in their own country.

The 57 signatories include Paul Butler, Anglican bishop of Durham; John Davies, archbishop of Wales; Susan Brown, moderator of the Church of Scotland; Naser Haghamed, chief executive of Islamic Relief Worldwide; Harun Khan, secretary general of the Muslim Council of Britain; and Paul Anticoni, chief executive of World Jewish Relief.

Faith leaders and religious bodies in countries including Brazil, South Sudan, Colombia, Haiti, Bangladesh and Sri Lanka have also signed the letter.

The signatories say in the letter that the UN’s global compact on refugees and migration, due to be signed this year, “regrettably provide scant attention to the ignored millions, forced out of their homes but still within their countries of origin”.

The international community “must ensure that internally displaced people receive the protection and support they so desperately need”, said the faith leaders, who want governments to join the GP20 plan of action.

More than 40 million people are refugees in their own countries, known as IDPs (internally displaced people). The number of new IDPs associated with conflict and violence almost doubled last year, from 6.8m in 2016 to 11.8m.

Many internal refugees remain in camps and “temporary” accommodation for years or even decades.

Amanda Khozi Mukwashi, chief executive of Christian Aid, the letter’s coordinator, said: “If not at the United Nations, then where will the voice of internally displaced women, men and children be heard? Where can their issues be dealt with? Who will bring together global efforts and resources so that they are not left behind? If not the UN, then who else?”

Anticoni said: “There are now unimaginable numbers of people fleeing conflict and persecution and becoming displaced within their own countries. These people are often hidden, denied access to support and protection and extremely vulnerable. We join our fellow faith-based agencies in calling for greater support and assistance to prevent, mitigate and respond to this scourge on humanity.”

Haghamed said: “My family and I had to flee our home in Eritrea because of conflict when I was 13. I will never forget what happened. We fled on foot and walked for days just to reach the border. And yet, I was lucky compared to what displaced people have to endure today.

“As faith groups, we are urging governments to fulfil their obligations towards their own displaced and calling on world leaders at the UN to make the safety, dignity and wellbeing of millions of displaced people a key priority.”

The letter will be discussed at the UN’s advisory council on faith on Friday.