New footage has been released showing freed Assyrian Christians worshipping after being held hostage by Islamic State for a year.

Posted to the Facebook page of the Assyrian Church of the East Relief Organisation (ACERO), which helped facilitate the hostages' release, the video shows 43 Christians singing hymns of praise.

"They have remained steadfast in their Christian faith despite a horrific year-long trial," a caption accompanying the clip reads.

The group were the last remaining hostages of more than 200 Assyrians abducted in northern Syria in February last year. Speaking to Christian Today, a spokesman for ACERO branded their release "a ray of light from amidst the darkness".

"This is the culmination of the tireless efforts of the Assyrian Church of the East in Syria and the church's international aid agency, ACERO," Joseph Haweil said.

"The captives who have been incrementally released over the last year have suffered inordinate psychological trauma. The attempted destruction of Assyrian continuity in Syria is only the latest instalment in more than a decade of intense persecution suffered by the indigenous Assyrians throughout the Middle East.

"Today however the Assyrian people have witnessed a ray of light from amidst the darkness. We pray that all of Syria's suffering people may also see this light of hope."

Though ACERO has not confirmed how much money was exchanged in return for the release of the hostages, an anonymous Syrian Christian source told AP that "millions of dollars" was paid.

Initially, ISIS militants demanded a ransom of around $100,000 per hostage, but when it became clear that the Assyrian community could not afford it, the amount was lowered.

A Demand for Action (ADFA), a campaign group for minorities in the Middle East, yesterday celebrated the release of the captives.

"As a human rights organization dedicated to work for the ethno-religious minorities, we are very thankful for the great leadership the Assyrian Church of the East has shown throughout these times and thank the Assyrian Church of the East Relief Organization for their help and tireless work to support the freed hostages," an ADFA statement said.

"We now begin to focus on re-building lives, and we start this by pressuring the United Nations to recognize the ongoing genocide taking place against these minorities who are tired of running.

"We must take action to bring awareness to what is really taking place in the Middle East. After the EU passed the resolution to recognize the atrocities taking place as genocide, it's now up to the United Nations turn to show true leadership and answer the calls and cries of all those whom have been affected and continue to be affected. The persecution of minorities must end."

Since the attacks last February, ISIS has besieged several ancient Assyrian sites, including the Iraqi city of Nimrud, the village of Khorsabad, and Hatra, a 2,000-year-old city.

An ancient branch of Christianity, the Assyrian Church of the East has roots dating back to the 1st century AD. Assyrian Christians speak Aramaic, the language of Jesus, and have origins in ancient Mesopotamia – a territory which spreads across northern Iraq, north-east Syria and south-eastern Turkey. Before the outbreak of civil war in 2011, an estimated 40,000 Assyrians lived in Syria.